Previously, the script didn't distinguish between the scheduled RHEL-X
nightly pipeline and the scheduled RHEL GA pipeline when reporting
status back to GitHub. Moreover the scheduled RHEL GA pipeline on GitLab
had RHEL_MAJOR variable set to "9". As a result, the scheduled RHEL GA
pipeline status has been reported to GitHub as "Schutzbot on GitLab,
RHEL-9-nightly", which effectively overrode the RHEL-9 nightly pipeline
status for the same commit.
Fix the script reporting the status back to GitHub, to take the NIGHLY
variable value into consideration when building up the status context.
I've also modified the RHEL GA scheduled pipeline settings in GitLab to
not specify any RHEL_MAJOR, which was a relict from pre-RHEL-10 days.
Signed-off-by: Tomáš Hozza <thozza@redhat.com>