Summary:
Clean-up some old un-needed code.
Move some unit-test preperation steps to the build stage, so that they do not to be re-done for
subsequent test and re-test jobs.

Test Plan:
jenkins regular build and test
jenkins re-test with and without test filter
Jenkins: test regex: .*PgLeaderChange.*

Reviewers: jharveysmith

Reviewed By: jharveysmith

Subscribers: devops

Differential Revision: https://phorge.dev.yugabyte.com/D39161