Add quick fix to Big5 Workload for integration tests

[IanHoang]

Description

Integration Tests in OpenSearch Benchmark repository are failing due to the following error:

Error: _test.py::test_list_workloads[in-memory-it] [ERROR] Cannot list. Could not load '/home/runner/work/opensearch-benchmark/opensearch-benchmark/.benchmark/benchmarks/workloads/default/big5/workload.json': Expecting value: line 20 column 29 (char 412). Lines containing the error:

        {
          "source-url": "",
          "source-file": "documents.json",
          "document-count": ,
----------------------------^ Error is here
          "uncompressed-bytes": ,
          "compressed-bytes": 1

This PR adds some changes to get around this issue

List any issues this PR will resolve, e.g. Closes [...].

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[gkamat]

Thanks for the fix.

[opensearch-trigger-bot]

The backport to 1 failed:

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

To backport manually, run these commands in your terminal:

# Fetch latest updates from GitHub
git fetch
# Create a new working tree
git worktree add ../.worktrees/backport-1 1
# Navigate to the new working tree
pushd ../.worktrees/backport-1
# Create a new branch
git switch --create backport/backport-168-to-1
# Cherry-pick the merged commit of this pull request and resolve the conflicts
git cherry-pick -x --mainline 1 3b451ecb254a554674ea664023f5803ebf8a0d2b
# Push it to GitHub
git push --set-upstream origin backport/backport-168-to-1
# Go back to the original working tree
popd
# Delete the working tree
git worktree remove ../.worktrees/backport-1

Then, create a pull request where the base branch is 1 and the compare/head branch is backport/backport-168-to-1.