Deprecate and remove Pseudonymizer
### Problem to solve
The Meltano team added the [Pseudonymizer feature](https://docs.gitlab.com/ee/administration/pseudonymizer.html) in 2018. As far as I can tell, no one really uses it, and it causes some production-level issues with large databases that I raised a while ago.
### Proposal
- [x] [Deprecate](https://docs.gitlab.com/ee/development/deprecation_guidelines/#when-can-a-feature-be-deprecated) Pseudonymizer. See https://gitlab.com/gitlab-org/gitlab/-/merge_requests/77249 and https://gitlab.com/gitlab-org/gitlab/-/merge_requests/77582
- [x] Remove Pseudonymizer in %15.0 (in a major release because it could be considered a breaking change).
### Related links
- [3 MRs that introduced Pseudonymizer](https://gitlab.com/groups/gitlab-org/-/merge_requests?scope=all&state=merged&author_username=mbergeron&search=Pseudonymizer)
Thoughts @mbergeron @DouweM @deuley?
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