Summary:
Wait for both producer and consumer tablets to split before performing overlap validation.
Added higher timeout for the sanitizer builds and introduced a short sleep between writes.

ReEnable all mac tests.

Fixes #19008
Jira: DB-7833

Test Plan: xcluster-tablet-split-itest

Reviewers: jhe, xCluster

Reviewed By: jhe

Subscribers: svc_phabricator, ybase

Differential Revision: https://phorge.dev.yugabyte.com/D39974