Optimize ObjId2FullSidMap::extractObjectId

[quijote]

Monitoring of one of our Jenkins instances showed that ObjId2FullSidMap::extractObjectId was a major CPU hotspot.

This PR attempts to make the code significantly faster.

Testing done

The change was tested with the newly created functional test (ObjId2FullSidMapTest::testExtractObjectId) and the newly created microbenchmark (ObjId2FullSidMapTest::testExtractObjectIdPerformance).

On my local machine the benchmark reported the following with the original code:

Median duration per call (nanos): 981

With the new code the benchmark reports:

Median duration per call (nanos): 34

So, this suggest that the new code is roughly 28 times faster than the previous one for typical input.

Submitter checklist

• Make sure you are opening from a topic/feature/bugfix branch (right side) and not your main branch!
• Ensure that the pull request title represents the desired changelog entry
• Please describe what you did
• Link to relevant issues in GitHub or Jira
• Link to relevant pull requests, esp. upstream and downstream changes
• Ensure you have provided tests - that demonstrates feature works or fixes the issue

[timja]

Thanks!

[timja]

FWIW JMH benchmarks are supported with something like this:
https://github.com/jenkinsci/junit-sql-storage-plugin/blob/master/src/test/java/io/jenkins/plugins/junit/storage/database/benchmarks/TrendGraphBenchmark.java

in case you are interested in converting but probably not worth it.

unsure if its worth committing this but certainly useful to provide it demonstrating the change.