Fix triggering rules for the "tarball-create" job

Fix triggering rules for the "tarball-create" job

Commit de35d321f03799c6ca723121d97af6ff82611ef4 (a backport of commit
4d5d3b75da12a6e4c1180bc003d88badf52cb514) did not account for the fact
that the "tarball-create" GitLab CI job is not created for manually
triggered pipelines.  This prevents manual pipeline creation from
succeeding as it causes the "gcc:tarball" job to have unsatisfied
dependencies.  Make sure the "tarball-create" job is created for
manually triggered pipelines to allow such pipelines to be started
again.

(cherry picked from commit 233294d7503b126fbad7004bd97aa271d41ed712)