Partially addresses #47424.

This removes all usage of soft removals except for the "pending delete"
system implemented for projects. This in turn simplifies all the query
plans of the models that used soft removals. Since we don't really use
soft removals for anything useful there's no point in keeping it around.

This _does_ mean that hard removals of issues (which only admins can do
if I'm not mistaken) can influence the "iid" values, but that code is
broken to begin with. More on this (and how to fix it) can be found in
https://gitlab.com/gitlab-org/gitlab-ce/issues/31114.

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/37447

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

- they can have owner,
- they can be edited,
- they have description,
- you can take ownership of them

They were Rails' default and are unnecessarily overridden.
Signed-off-by: NDavid Wagner <david@marvid.fr>

This reverts commit 3e991230.

# Conflicts:
#	app/models/project.rb

In 8278b763 the default behaviour of annotation
has changes, which was causing a lot of noise in diffs. We decided in #17382
that it is better to get rid of the whole annotate gem, and instead let people
look at schema.rb for the columns in a table.

Fixes: #17382

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