Implement SAML Group Sync worker link limit

Follow-up from !46700 (merged)

Currently, the number of group link ids sent to the GroupSamlGroupSyncWorker is unbounded. Realistically most users will probably have few group links. But in the interest of ensuring Redis doesn't store an unnecessarily large list of group ids we should institute some sane limit. At the same time the limit shouldn't be so low it reduces the usefulness of the feature.

Worker call example:

In code: https://gitlab.com/gitlab-org/gitlab/-/blob/c9a8a2f0f1a4ae1ea39eb264121caf8e86afa466/ee/lib/gitlab/auth/group_saml/membership_updater.rb#L35

GroupSamlGroupSyncWorker.perform_async(<user>, <group>, [1,2,3,4,5,6,...])

The array at the end of the above example is the one we ought to limit.

Is 500 a limit that still ensures Redis doesn't have to store too much data but also is useful for our largest customers?