internal/log: allow RecordLogger to ignore certain logs

[lievan]

What does this PR do?

Some unit tests in the tracer assert based on the content or positioning of log messages (example). When new log messages are added (e.g. by appsec) these tests will fail. To workaround this, we've previously introduced a removeAppsec method that removes strings which contain appsec: from recorded logs. This PR introduces an alternate solution to directly ignore certain substrings using RecordLogger while logging.

More specifically, this PR:

• removes testLogger from the tracer package. testLogger has a near identical implementation to RecordLogger in the internal/log package, so we can just use RecordLogger instead.
• adds a Ignore method to RecordLogger that allows us to ignore logs which contain certain substrings.
• edits unit tests in the tracer package to use RecordLogger and Ignore to ignore appsec logs

Motivation

Introduces a slightly friendlier interface for ignoring logs in comparison to creating custom functions that remove log messages, which may be useful when new features that use logging (e.g. instrumentation telemetry) are introduced.

Describe how to test/QA your changes

Reviewer's Checklist

• If known, an appropriate milestone has been selected; otherwise the Triage milestone is set.
• Changed code has unit tests for its functionality.
• If this interacts with the agent in a new way, a system test has been added.

[ajgajg1134]

This seems pretty reasonable to me! Perhaps at some point in the future we can use / interact with more structured logs that would make this sort of thing easier and less error-prone than just a string contains, but I think that's a conversation for another day perhaps as this is an improvement over what exists now.

[pr-commenter]

Benchmarks

Comparing candidate commit 182085e in PR branch evan.li/ignore-logs with baseline commit 3895e95 in branch main.

Found 0 performance improvements and 0 performance regressions! Performance is the same for 18 metrics, 0 unstable metrics.