Add an instruction-level performance microbenchmark for findAndModify.

Before implementation, check existing microbenchmark coverage to avoid duplication.

The benchmark will be added to PR checks and/or a triaged context in separate work within the project.

Acceptance Criteria:

• An findAndModify microbenchmark is implemented and running on the waterfall.
• The benchmark should meet the following standards:
  • Trends with our HVWs
  • Low noise
  • Short