performance + refactoring + fix: delegated roles update (add/remove) metadata

[kairoaraujo]

Improve bootstrap performance for hash bins (large number such as 16384 PyPI/RubyGems)

Before : Added 2048 hash bins in 119.36732602119446 seconds
Current: Added 2048 hash bins in 1.8565280437469482 seconds

PyPI (PEP 458) and RubyGems size creation:
Added 16384 hash bins in 15.13554310798645 seconds

Fix query to bump empty target files

the actual crud query fails if there is not target files (artifacts) in
the database (TargetFiles) and do not return the the Target Role.

This commmit fixes this query using isouter

https://docs.sqlalchemy.org/en/20/orm/queryguide/query.html#sqlalchemy.orm.Query.join.params.isouter

Refactor: update_snapshot.

Split update_snapshot in a functional way for:

• updating targets roles for hashbin delegated roles
• updating targets roles for custom delegated roles

TODO:

Improve the performance and use the celery multi-threading

   repository-service-tuf-worker-1  | [2024-10-14 06:00:00,132: DEBUG/ForkPoolWorker-9] PRE_RUN: bump_online_roles
   repository-service-tuf-worker-1  | [2024-10-14 06:00:00,417: DEBUG/ForkPoolWorker-9] Checking for expired hash bin roles (16384 bins)
   repository-service-tuf-worker-1  | [2024-10-14 06:01:26,330: DEBUG/ForkPoolWorker-9] Total 16384 expired roles in 85.92996311187744s
   repository-service-tuf-worker-1  | [2024-10-14 06:04:07,217: INFO/ForkPoolWorker-9] Task app.repository_service_tuf_worker[bump_online_roles] succeeded in 247.09811807099322s: True

• is_expired: ~90s
• _update_targetfiles_hashbin_delegated_roles: ~250s
• _update_targetfiles_custom_delegated_roles (Nice to Have)