[PLAT-14981]Increase default slow query length

Summary: Increase default runtime config value to 16KB

Test Plan: Verified the new value is reflected in runtime config UI.

Reviewers: svarshney

Reviewed By: svarshney

Subscribers: yugaware

Differential Revision: https://phorge.dev.yugabyte.com/D37409

managed/src/main/resources/reference.conf

@@ -1083,7 +1083,7 @@ yb {
        order_by = "total_time"
        set_enable_nestloop_off = true
        timeout_secs = 180
-       query_length = 1024
+       query_length = 16384
     }
 
     # Different wait times for live queries