Server Side Request Forgery mitigation bypass

Closes #2872

See merge request gitlab/gitlabhq!3205

These are not required because MySQL is not
supported anymore

None of this code can be reached any more, so it can all be removed

Use correct parent when committing in WebIDE

See merge request gitlab-org/gitlab-ce!29598

When passing start_branch on committing from the WebIDE, it's possible
that the branch has changed since editing started, which results in the
change being applied on top of the latest commit in the branch and
overwriting the new changes.

By passing the start_sha instead we can make sure that the change is
applied on top of the commit which the user started editing from.

Whenever we use the rugged implementation, we are going straight to disk
so we want to bypass the disk access check.

When we can't resolve the hostname or it is invalid, we shouldn't
even perform the request. This fix also fixes the problem the
SSRF rebinding attack.

We can't stub feature flags outside example blocks. Nevertheless,
there are some actions that calls the UrlBlocker, that are performed
outside example blocks, ie: `set` instruction.

That's why we have to use some signalign mechanism outside the scope
of the specs.

Use transactions in JS feature specs

Closes #60207

See merge request gitlab-org/gitlab-ce!27496

Log memory stats after running each spec file and compile the report.