Restores GitLab optimization but with caching and pagination fixes.

Co-authored-by: Lukas Eipert <leipert@users.noreply.github.com>

https://docs.gradle.org/current/dsl/org.gradle.api.artifacts.dsl.DependencyHandler.html#N17198

This reverts commit 9779d77e.

1. `findPr` also includes the `source_branch` API parameter which
shortens execution time considerably
2. `getPrList` also filters `author_id` for the renovate's user

All ts files have to have an `import` or `export` because of
`isolatedModules` flag.

This reverts commit 69566652.

fixes #3799

 fix(bitbucket-server): delay pr refresh

Closes #3944

Closes #3938

Closes https://github.com/renovatebot/config-help/issues/275

GitLab self-hosted users now no longer need to manually configure gitAuthor if it matches with the bot account they’re using.

Fixes #3879.