[#25793] CDC: Reduce pub refresh interval to 15 minutes

Summary:
This diff reduces the the default value of the flag
`cdcsdk_publication_list_refresh_interval_secs` to 15 minutes from the current default value of 1 hr.
Jira: DB-15085

Test Plan: Jenkins: test regex:.*CDC.*

Reviewers: skumar, siddharth.shah

Reviewed By: siddharth.shah

Subscribers: ycdcxcluster

Differential Revision: https://phorge.dev.yugabyte.com/D41538

src/yb/cdc/cdcsdk_virtual_wal.cc

@@ -47,7 +47,7 @@ DEFINE_RUNTIME_uint32(cdcsdk_max_consistent_records, 500,
     "cdc_vwal_use_byte_threshold_for_consistent_changes flag is set to false.");
 
 DEFINE_RUNTIME_uint64(
-    cdcsdk_publication_list_refresh_interval_secs, 3600 /* 1 hour */,
+    cdcsdk_publication_list_refresh_interval_secs, 900 /* 15 mins */,
     "Interval in seconds at which the table list in the publication will be refreshed");
 
 DEFINE_RUNTIME_uint64(