Makes the -test_mode option, which runs the invariant_checker tool, available in release builds. This fixes the drcacheoff.rseq test failures on GA CI when rseq is actually available in our upgrade to Ubuntu 20.04.
Removes the test failure ignore rule for Jenkins as this also fixes the AArch64 failure for the same test.
Fixes #4924 (closed) Issue: #4924 (closed), #4953 (closed)