[enhancement](config) Change segments_key_bounds_truncation_threshold default to 36 (#61984)

Enable segments key bounds truncation by default with threshold 36 bytes to reduce rowset metadata memory usage.

Author: bobhan1

be/src/common/config.cpp

@@ -1711,7 +1711,7 @@ DEFINE_mBool(enable_update_delete_bitmap_kv_check_core, "false");
 DEFINE_mBool(enable_fetch_rowsets_from_peer_replicas, "false");
 // the max length of segments key bounds, in bytes
 // ATTENTION: as long as this conf has ever been enabled, cluster downgrade and backup recovery will no longer be supported.
-DEFINE_mInt32(segments_key_bounds_truncation_threshold, "-1");
+DEFINE_mInt32(segments_key_bounds_truncation_threshold, "36");
 // ATTENTION: for test only, use random segments key bounds truncation threshold every time
 DEFINE_mBool(random_segments_key_bounds_truncation, "false");
 // p0, daily, rqg, external