Disable coverage for debug builds
Prior to #225 (closed), coverage pipelines did not contain debug builds.
- Last working pipeline: https://gitlab.com/redhat/red-hat-ci-tools/kernel/cki-internal-pipelines/cki-trusted-contributors/-/pipelines/1199391570
- First broken pipeline: https://gitlab.com/redhat/red-hat-ci-tools/kernel/cki-internal-pipelines/cki-trusted-contributors/-/pipelines/1203832079
AC:
- disable debug builds in gcov pipelines