Add proper failure handling for CREATE commands that cannot be run inside a transaction block

As we do for CREATE DATABASE commands in https://github.com/citusdata/citus/pull/7483, we might want to implement proper failure handling mechanisms for other CREATE commands too.

As of today, the only example to this is `CREATE INDEX CONCURRENTLY`.

(Searching for where do we set `cannotBeExecutedInTransaction` to `true` within the code-base verifies this^.)