[Document Retention] Increase to 3000 documents scanned per run (#29001)

Increase max scanned documents from 1500 -> 3000.

GitOrigin-RevId: 585e83b669498158f431aeaedd675889cb3befc9

crates/common/src/knobs.rs

@@ -449,7 +449,7 @@ pub static DOCUMENT_RETENTION_BATCH_INTERVAL_SECONDS: LazyLock<Duration> = LazyL
 /// there are a bunch of writes at single timestamp. Then, we go until there are
 /// no more writes at that timestamp.
 pub static DOCUMENT_RETENTION_MAX_SCANNED_DOCUMENTS: LazyLock<usize> =
-    LazyLock::new(|| env_config("DOCUMENT_RETENTION_MAX_SCANNED_DOCUMENTS", 1500));
+    LazyLock::new(|| env_config("DOCUMENT_RETENTION_MAX_SCANNED_DOCUMENTS", 3000));
 
 /// Size at which a search index will be queued for snapshotting.
 pub static SEARCH_INDEX_SIZE_SOFT_LIMIT: LazyLock<usize> =