PR #87188 - backupccl: drop admin only check for CREATE SCHEDULE

[cockroach-teamcity]

Exalate commented:

Related PR: cockroachdb/cockroach#87188
Commit: cockroachdb/cockroach@1a5811e

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Release note (sql change): CREATE SCHEDULE is no longer an
admin only operation. Users should grant the appropriate BACKUP
privileges on the targets they wish to back up as part of the schedule.

Cluster backups - require admin or system privilege BACKUP

DB backups - require datbase privilege BACKUP

Table backups - require table privilege BACKUP

Jira Issue: DOC-5558