fix: add no-op mode and ensure item cleanup for disk cache

[sprutton1]

• Allows the disk cache cleanup to be run in no-op for validation
• Adds a config setting for adjusting the disk cache cleanup mode
• Re-enable disk cache cleanup
• Track and report on the disk cache cleanups
• Ensure we are removing both the index and the content when we remove from the disk cache

2024-10-14T15:25:13.975559Z  INFO ThreadId(57) si_layer_cache::disk_cache: Disk cache cleanup mode no-op removed 0 out of 0 expired items
2024-10-14T15:26:13.984540Z  INFO ThreadId(50) si_layer_cache::disk_cache: Disk cache cleanup mode no-op removed 0 out of 368 expired items

2024-10-14T16:12:05.830532Z  INFO ThreadId(64) si_layer_cache::disk_cache: Disk cache cleanup mode remove removed 0 out of 0 expired items
2024-10-14T16:12:15.869308Z  INFO ThreadId(30) si_layer_cache::disk_cache: Disk cache cleanup mode remove removed 133 out of 133 expired items
2024-10-14T16:12:25.876136Z  INFO ThreadId(60) si_layer_cache::disk_cache: Disk cache cleanup mode remove removed 0 out of 0 expired items

[sprutton1]

/try