[DocDB] Add log line when servicing RestoreSnapshotSchedule

[ritoban23]

Description

Fixes #28707

This PR adds a log line when the master leader services a RestoreSnapshotSchedule RPC request. This follows the same pattern used by other "major" RPC handlers like CreateSnapshot, DeleteSnapshot, and RestoreSnapshot.

Changes

• Added LOG(INFO) line in CatalogManager::RestoreSnapshotSchedule()
• Log includes schedule ID and restore time for debugging
• Follows existing logging patterns in the codebase

[CLAassistant]

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