RestartCatalog command should take RSTL lock in X mode

RestartCatalog can be interruptible by stepdown after SERVER-40604 because ViewCatalog::reloadIfNeeded takes an interruptible collection lock. It violates our assumption that restartCatalog can not be interrupted.

Although in production stepdown can never happen when restartCatalog gets called by rollback because rollback already takes RSTL X lock, some tests that exercise both restartCatalog command and stepdown could have this issue. So we should take RSTL X lock in restartCatalog.