[BUG] Missing validations in shallow snapshot V2 repo creation

[sachinpkale]

Describe the bug

• While creating repository for shallow snapshot V2, we have following validations missing:
  • There can be multiple repositories with the shallow v2 flag enabled.
  • Repo name can contain a delimiter that is used in the pinning entity

Without these validations, remote store data cleanup will not be straightforward and can lead to zombie data.

[sachinpkale]

Need to get this change in 2.17. PR: #15911

[ashking94]

Closing this issue since the associated PR is already merged.
[Triage - attendees 1 2 3 4 5]