Geo: Update usages of files_max_capacity

What does this MR do?

files_max_capacity limits both RegistrySyncWorker and FileDownloadDispatchWorker concurrent jobs like so:

• FileDownloadDispatchWorker may schedule up to 100% of files_max_capacity
• RegistrySyncWorker may schedule up to 25% of files_max_capacity
• Combined, they may use up to 125% of files_max_capacity.

Now that there are 4 models replicated by RegistrySyncWorker vs 3 models replicated by FileDownloadDispatchWorker, we should adjust this. This MR does this:

• FileDownloadDispatchWorker may schedule up to 50% of files_max_capacity
• RegistrySyncWorker may schedule up to 50% of files_max_capacity
• Combined, they may use up to 100% of files_max_capacity.

Note that: #294074 (closed) is separate issue. And when legacy blob models (uploads, lfs, artifacts) are migrated to the Geo framework, FileDownloadDispatchWorker will go away and we can make RegistrySyncWorker use all of files_max_capacity.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.