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