Limit the action suffixes in transaction metrics

What does this MR do?

There seem to be a lot of cases where the suffix of an action (e.g. ".html") is set to bogus data, such as "/" or entire URLs. This can increase cardinality of our metrics, and isn't very useful for monitoring and filtering. To work around this, we enforce a whitelist containing a few suffixes we actually care about. Suffixes not supported will be grouped under the action without a suffix. This means that a request to "FooController#bar.jpeg" will be assigned to "FooController#bar".

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Tests added for this feature/bug
• Conform by the code review guidelines
  • Has been reviewed by a Backend maintainer
  • Has been reviewed by a Database specialist
• Conform by the merge request performance guides
• Conform by the style guides
• If you have multiple commits, please combine them into a few logically organized commits by squashing them
• End-to-end tests pass (package-and-qa manual pipeline job)