Collect coverage once
Only collect and show coverage for the main unit-test job, instead of for all unit test jobs.
This change speeds up all non-main unit-test jobs on CI:
- unit-test-ubsan-2204 runs in 7 minutes instead of 14 minutes.
- unit-test-asan-2204 runs in 8 minutes instead of 11 minutes.
- unit-test-portable-xxx run in 8 minutes instead of 12 minutes.
Edited by Maik Nijhuis