Summary:
Alter table request could arrive while table is being prepared.
It could ruin table states transition logic.

Fixed by rejecting alter table while table is being prepared.

Also removed explicit vmodule setup in tests.
If it is necessary to execute test with vmodule settings we could always use `--test-args --vmodule=...` way.
Which is blocked by explicit value for vmodule flag.
Jira: DB-14280

Test Plan: ./yb_build.sh fastdebug --gcc11 --gtest_filter CDCSDKYsqlTest.TestAddManyColocatedTablesOnNamesapceWithStream -n 40

Reviewers: zdrudi, xCluster, hsunder

Reviewed By: zdrudi

Subscribers: ybase, yql

Tags: #jenkins-ready

Differential Revision: https://phorge.dev.yugabyte.com/D40367