The test environment setup in the CI scripts has been consolidated and
deduplicated to remove redundancies and simplify test flag management.
* ps/ci-consolidate-test-variables:
ci: don't override initial branch name in testbed job
ci/lib: add another NO_RUST build using glibc
t: honor default ref storage format
ci/lib: merge switches for specific job names
ci/lib: deduplicate test variables by pattern matching
ci/lib: always set GIT_TEST_USE_SET_E on Linux jobs
ci: consolidate setup of test environment
Junio C Hamano
dbb1431606