RUMM-1588 + RUMM-1610 Update E2E test monitors to new metric format

[ncreated]

What and why?

⚙️ This PR updates our E2E test monitors to new format:

• it adds feature tag (logs | trace | rum | core) to each monitor;
• it adds monitor:behavior tag to all monitors asserting data;
• it adds monitor:performance tag to all monitors asserting performance;
• from now on, all performance spans use "perf_measure" span with test method sent as a resource name.

It also adds a bonus for troubleshooting, now each monitor renders its corresponding E2E test code in monitor UI, e.g.:

This helps understanding each monitor, especially if it expects "data" or "no data".

How?

• I added ${{feature}} variable to monitors template - it has no default value, so linter will emit an error if not specified.
• Both monitor:behaviour and monitor:performance tags are hardcoded in each template.
• I updated code to differentiate resource_name for each span and use common operation_name.

Code rendering is done through template system. Code is parsed while reading monitors from test files.

I regenerated all monitors by first deleting them, and then running terraform apply.

Review checklist

• Feature or bugfix MUST have appropriate tests (unit, integration)
• Make sure each commit and the PR mention the Issue number or JIRA reference

[ncreated]

It's easy to come up with an dummy edge case where this won't work, e.g.:

func testFunction() {
   // {
}

but the linter message comes handy:

It didn't require any code formatting change to make it work, and I consider this "good enough" for the value it is adding. In a very rare edge cases where this would not work (I can't come up with any), this could be easily muted in the test code (e.g. by // }).