Create separate transport action for render search template action

[cwperks]

Description

Companion PR in security: opensearch-project/security#3689

Separates the transport action that handles POST /_render/template into a separate transport action from GET /_search/template to resolve an issue with permission the render template endpoint.

The transport action that handles both of these requests is overloaded and it makes permissioning these endpoints a challenge in the security plugin.

1. GET /_search/template or GET /<list_of_indices>/_search_template is a form of a search request and should consider whether the user has permission to search on the list of indices provided in the request when evaluating whether the user has permission to perform the search template request.

2. In contrast, POST /_render/template is a simulation and never actually queries data. See the linked issue for an example of a search template request. From the security plugin POV, this type of request does not need indices when evaluating whether the user has permission to perform the request and can be treated as a cluster permission.

This PR separates the transport action that handles both so that permissions can handle both of these types of requests. There is no functionality change on this PR, the testing for this is added in the companion PR.

Related Issues

Resolves opensearch-project/security#3672

Check List

• New functionality includes testing.
  • All tests pass
• New functionality has been documented.
  • New functionality has javadoc added
• Failing checks are inspected and point to the corresponding known issue(s) (See: Troubleshooting Failing Builds)
• Commits are signed per the DCO using --signoff
• Commit changes are listed out in CHANGELOG.md file (See: Changelog)
• Public documentation issue/PR created

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[github-actions]

❌ Gradle check result for 61b9dfa: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[cwperks]

• Gradle check failed with flaky test: [BUG] Flaky Test - org.opensearch.index.shard.IndexShardTests.testCommitLevelRestoreShardFromRemoteStore  #10704

[github-actions]

❌ Gradle check result for 61b9dfa: null

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[peternied]

@cwperks Can you please create an issue on the GitHub action failures reported in #11170 (comment)

Jenkins Workflow Url: https://build.ci.opensearch.org/job/gradle-check/31127/
time pass: 2790
parse error: Invalid numeric literal at line 1, column 10
Complete the run, checking results now......
Please check jenkins url for logs: https://build.ci.opensearch.org/job/gradle-check/31127/
Result: null

[cwperks]

@peternied Opened an issue: #11574

[github-actions]

❕ Gradle check result for 61b9dfa: UNSTABLE

• TEST FAILURES:

      1 org.opensearch.remotestore.multipart.RemoteStoreMultipartIT.testRequestDurabilityWhenRestrictSettingImplicitFalse

Please review all flaky tests that succeeded after retry and create an issue if one does not already exist to track the flaky failure.

[codecov]

Codecov Report

Attention: 11 lines in your changes are missing coverage. Please review.

Comparison is base (00dd577) 71.03% compared to head (61b9dfa) 71.29%.
Report is 4 commits behind head on main.

Files	Patch %	Lines
...script/mustache/TransportSearchTemplateAction.java	0.00%	5 Missing ⚠️
...ch/script/mustache/RenderSearchTemplateAction.java	0.00%	3 Missing ⚠️
.../mustache/TransportRenderSearchTemplateAction.java	0.00%	2 Missing ⚠️
...cript/mustache/RestRenderSearchTemplateAction.java	0.00%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #11170      +/-   ##
============================================
+ Coverage     71.03%   71.29%   +0.25%     
- Complexity    58886    59141     +255     
============================================
  Files          4904     4906       +2     
  Lines        278154   278164      +10     
  Branches      40419    40419              
============================================
+ Hits         197600   198320     +720     
+ Misses        64091    63354     -737     
- Partials      16463    16490      +27     

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[opensearch-trigger-bot]

The backport to 2.x failed:

The process '/usr/bin/git' failed with exit code 128

To backport manually, run these commands in your terminal:

# Navigate to the root of your repository
cd $(git rev-parse --show-toplevel)
# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/OpenSearch/backport-2.x 2.x
# Navigate to the new working tree
pushd ../.worktrees/OpenSearch/backport-2.x
# Create a new branch
git switch --create backport/backport-11170-to-2.x
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 66d4e9e0d5fca1c50b84c08dccc9f5e9164c64c1
# Push it to GitHub
git push --set-upstream origin backport/backport-11170-to-2.x
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/OpenSearch/backport-2.x

Then, create a pull request where the base branch is 2.x and the compare/head branch is backport/backport-11170-to-2.x.

[peternied]

@cwperks Mind doing the backport when you get a chance?

[cwperks]

@peternied Opened manual backport: #11589