Pass skip_ci to CreateBranchWorker for first mirror sync

What does this MR do and why?

This is the caller-side change for the multi-release Sidekiq deployment:

Release	Changes	MR
19.3	Worker: Add skip_ci = false parameter	!247467 (merged) ✅ Merged
19.4 (this MR)	Caller: Start passing skip_ci argument	This MR

Now that CreateBranchWorker can accept the skip_ci argument (added in !247467 (merged)), this MR updates UpdateMirrorService to pass it:

• bulk_create calls (sync branch creation)
• schedule_async_batches arguments_proc (async branch creation)

The skip_ci value comes from skip_ci_for_non_default_branches? which returns:

• true on first sync → prevents pipeline explosion
• false on delta syncs → normal behavior

Multi-release deployment

Per Sidekiq compatibility guidelines:

When adding a new argument to a Sidekiq worker, the worker must be deployed first (accepting the argument with a default value), and callers updated in a subsequent release.

This ensures rolling deployments don't break when old Sidekiq workers receive new arguments.

MR acceptance checklist

• Tests added (included from !247467 (merged))
• Rebased onto master after !247467 (merged) merged
• Ready for review in 19.4

Related

• Parent issue: #598486 (closed)
• Follow-up issue: #607902 (closed)
• Preparatory MR (19.3): !247467 (merged)