Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/30642

Fixes https://sentry.gitlap.com/gitlab/gitlabcom/issues/26786/

Given a valid pipeline job, and a regex which wouldn't match to a jobs
trace, the stream of the trace would return the File object. This was
not the case when it matched a value, as that would have been return
from the block.

Now the `extract_coverage` method returns `nil` if no match was found.

When renaming, the argument on the projects hook API was forgotten. Now
one could successfully set it again.

The fix is a little ugly stylewise, but needed as the underlying model
still refers to it as build_events. This commit is to fix it, later we
should migrate the data to a new column. The edit on the spec file makes
sure it passes now, and will fail when we migrate the column.

Signed-off-by: NDmitriy Zaporozhets <dmitriy.zaporozhets@gmail.com>

Closes #29913

I started out as I missed the foreign key on ci_triggers and projects.
However, it seemed Yorick caught this already on gitlab-org/gitlab-ce!9388.

Still I found a missing foreign key, between the trigger requests and
triggers. This commit adds it, and removes the depend: :destroy on the
Rails model Ci::Triggers

Without repo permissions, pressing the "Edit" button on the blame page
will now prompt to Fork/Cancel.

Fix https://gitlab.com/gitlab-org/gitlab-ce/issues/30636