Remove gitlab files

These don't really serve a purpose now and aren't even recognized by
Gitea.

.gitlab/issue_templates/Bug.md

@@ -1,18 +0,0 @@
-<!--
-### Precheck
-
-* For support use https://git.pleroma.social/pleroma/pleroma-support or [community channels](https://git.pleroma.social/pleroma/pleroma#community-channels).
-* Please do a quick search to ensure no similar bug has been reported before. If the bug has not been addressed after 2 weeks, it's fine to bump it.
-* Try to ensure that the bug is actually related to the Pleroma backend. For example, if a bug happens in Pleroma-FE but not in Mastodon-FE or mobile clients, it's likely that the bug should be filed in [Pleroma-FE](https://git.pleroma.social/pleroma/pleroma-fe/issues/new) repository.
--->
-
-### Environment
-
-* Installation type (OTP or From Source):
-* Pleroma version (could be found in the "Version" tab of settings in Pleroma-FE): 
-* Elixir version (`elixir -v` for from source installations, N/A for OTP):
-* Operating system:
-* PostgreSQL version (`psql -V`):
-
-
-### Bug description

.gitlab/merge_request_templates/Release.md

@@ -1,6 +0,0 @@
-### Release checklist
-* [ ]  Bump version in `mix.exs`
-* [ ]  Compile a changelog
-* [ ]  Create an MR with an announcement to pleroma.social
-* [ ]  Tag the release
-* [ ] Merge `stable` into `develop` (in case the fixes are already in develop, use `git merge -s ours --no-commit` and manually merge the changelogs)