Limit VENDOR_TEST_REPOS git clone based on BUILD_LIST

Due to the increasing popularity of VENDOR_TEST_REPOS, we should Limit VENDOR_TEST_REPOS git clone based on BUILD_LIST. That is only git clone the related repos. This will help us to increase the efficiency of the test pipeline.
For example, if VENDOR_TEST_REPOS is set to functional and system test repo, for the test build that runs perf testing (i.e., BUILD_LIST=perf), neither functional or system repos should be git cloned.

Search the repository for VENDOR_TEST_REPOS, BUILD_LIST, and the git-clone entry point to understand how test builds select repositories. Verify that a perf build with functional and system repositories configured does not clone those unrelated repositories, while related repositories still clone.

Written by the indexing model from the issue text.