Add desired sharding keys for feature category `vulnerability_management`.

These tables have been identified as a [cell local tables](https://docs.gitlab.com/ee/development/database/multiple_databases.html#guidelines-on-choosing-between-gitlab_main_cell-and-gitlab_main_clusterwide-schema).
All cell local tables require a [sharding key](https://docs.gitlab.com/ee/development/database/multiple_databases.html#defining-a-sharding-key-for-all-cell-local-tables)
or a [desired sharding key](https://docs.gitlab.com/ee/development/database/multiple_databases.html#defining-a-desired_sharding_key-for-automatically-backfilling-a-sharding_key)

A desired sharding key has been automatically selected for these tables.
These keys were chosen as the desired sharding keys because the
table has a :belongs_to relationship to a table that itself has a `NOT NULL` sharding key.

Additionally, `gitlab_schema` has been set to `gitlab_main_cell` for any tables didn't use this schema already.
For these tables we have also added `allow_cross_joins`, `allow_cross_transactions` and
`allow_cross_foreign_keys`. These will silence any existing violations, allowing the pipeline to pass without
requiring further changes. In the future, we'll remove these `allow_...` statements and fix any violations as
they arise. You can read more about this in the [documentation for multiple databases](https://docs.gitlab.com/ee/development/database/multiple_databases.html)

We have assigned a random backend engineer from ~"group::threat insights" to review these changes.

Please confirm that:

- each of these tables can be classified as cell local
- the selected desired sharding key is appropriate
- the backfill configuration for the desired sharding key is correct

When you are finished, please request a review from the database maintainer suggested by Danger.
If you have any questions or concerns, reach out to @tigerwnz, @DylanGriffith or @manojmj.

If you would like to go through similar merged MRs so as to gather an understanding on this topic, you
can use [this](https://gitlab.com/gitlab-org/gitlab/-/merge_requests?scope=all&state=merged&label_name[]=automation%3Agitlab-housekeeper-authored) link.

This change was generated by
[gitlab-housekeeper](https://gitlab.com/gitlab-org/gitlab/-/tree/master/gems/gitlab-housekeeper)

Changelog: other