Remove dead search knob (#31185)

We stopped using v1 text search index format many months ago so we can delete this knob.

GitOrigin-RevId: f6813a25ffe2fd41ddd8aaf8f41b45fcf3781aab

Author: emmaling27

crates/common/src/knobs.rs

@@ -468,14 +468,6 @@ pub static DOCUMENT_RETENTION_MAX_SCANNED_DOCUMENTS: LazyLock<usize> =
 pub static SEARCH_INDEX_SIZE_SOFT_LIMIT: LazyLock<usize> =
     LazyLock::new(|| env_config("SEARCH_INDEX_SIZE_SOFT_LIMIT", 10 * (1 << 20))); // 10 MiB
 
-/// Size at which a v1 single segment text search index will be queued for
-/// snapshotting.
-///
-/// We use a larger value here because building single segment text search
-/// indexes is exponential, so building indexes infrequently reduces the overall
-/// time spent building the index.
-pub static TEXT_SEARCH_V1_INDEX_SIZE_SOFT_LIMIT: LazyLock<usize> =
-    LazyLock::new(|| env_config("SEARCH_INDEX_SIZE_SOFT_LIMIT", 50 * (1 << 20))); // 50 MiB
 /// Configures the search index worker's rate limit on pages processed per
 /// second.
 pub static SEARCH_INDEX_WORKER_PAGES_PER_SECOND: LazyLock<NonZeroU32> = LazyLock::new(|| {