The avatar logic has been moved from Project to Repository as this makes
caching easier. The logic itself in turn has been changed so that the
logo file names are cached in Redis. This cache is flushed upon pushing
a commit but _only_ if:
1. The commit was pushed to the default branch
2. The commit actually changes any of the logo files
If no branch or commit is given the cache is flushed anyway, this
ensures that calling Repository#expire_cache without any arguments still
flushes the avatar cache (e.g. this is used when removing a project).
Fixesgitlab-org/gitlab-ce#14363
Adjusted behavior so canceled builds tagged as allowed to fail do not fail build
## What does this MR do?
This diff changes the 'Allowed to fail' flag to also ignore canceled builds, whereas before, canceled builds could fail the suite even if they were marked as 'Allowed to fail'
dupe of !3258 to force a build
## Are there points in the code the reviewer needs to double check?
no
## Why was this MR needed?
Unexpected behavior as a user
## What are the relevant issue numbers?
## Screenshots (if relevant)

See merge request !3271
External Users
The user has the rights of a public user execpt it can never create a project, group, or team. Also it cant view internal projects.
Partially fix for both #4009 and #13938 (except the LDAP sync or a pattern to detect external users)

See merge request !3171
Feature specs that were using javascript took a long time to finish
(about 10x longer) and where hitting Poltergeist timeouts.
This modification skips using javascript with select2 selecbox, thus it
is faster, but this also does not check some JavaScript related
features.
`MergeRequest#source_sha` is expected to return the sha of the source
branch last commit.
But when a open Merge Request has no diff (e.g. all commits have already
been merged to the target branch), `merge_request.source_sha`
incorrectly returns `nil`.
This was un-noticed before – but now that !2217 has been merged,
it makes `Gitlab::Git::Commit.between` raise an
"Unexpected nil argument" exception.
This fixes the crash, by making sure that `source_sha` returns a
correct result even when there is no diff available.