Properly process all needs

Closes #65488

See merge request gitlab-org/gitlab-ce!31415

Currently, some of the jobs with `needs:`
would be processed in stages, it means
that `when:` for such jobs would not be
respected.

This changes the behavior to have a separate
execution paths for jobs with `needs:`.

This changes `needs:` from weak reference
to have a strong reference.

This means that job will not be created
unless all needs are present as part of
a pipeline.

This implements the support for `needs:` keyword
as part of GitLab CI. That makes some of the jobs
to be run out of order.

Adds Job specific variables to facilitate specifying variables when
running manual jobs.

Often live traces are removed even though the archived trace
doesn't exist. This commit checkes the existence strictly.

This commit reverts the previously introduced concurrent pipeline
schedule creation which was a viable solution for mitigating
inconsistent pipeline schedule by Sidekiq Memory Killer.

This backports all EE schema changes to CE, including EE migrations,
ensuring both use the same schema.

== Updated tests

A spec related to ghost and support bot users had to be modified to make
it pass. The spec in question assumes that the "support_bot" column
exists when defining the spec. In the single codebase setup this is not
the case, as the column is backported in a later migration. Any attempt
to use a different schema version or use of "around" blocks to
conditionally disable specs won't help, as reverting the backport
migration would also drop the "support_bot" column. Removing the
"support_bot" tests entirely appears to be the only solution.

We also need to update some foreign key tests now that we have
backported the EE columns. Fortunately, these changes are very minor.

== Backporting migrations

This commit moves EE specific migrations (except those for the Geo
tracking database) and related files to CE, and also removes any traces
of the ee/db directory.

Some migrations had to be modified or removed, as they no longer work
with the schema being backported. These migrations were all quite old,
so we opted for removing them where modifying them would take too much
time and effort.

Some old migrations were modified in EE, while also existing in CE. In
these cases we took the EE code, and in one case removed them entirely.
It's not worth spending time trying to merge these changes somehow as we
plan to remove old migrations around the release of 12.0, see
https://gitlab.com/gitlab-org/gitlab-ce/issues/59177 for more details.

Preventing blocked users and their PipelineSchdules from creating new Pipelines

Closes #47756

See merge request gitlab-org/gitlab-ce!27318

Fixing the bug