Follow-up patch to fix test failure in create-big.test.

The original patch changed the behavior for ALTER TABLE ... RENAME
so that it now blocks if it can't acquire metadata lock on the
target table (matching behavior of RENAME TABLE). Create-big.test
tested for the old behavior where ALTER TABLE ... RENAME in such
cases did not block but reported an error immediately instead.

This patch fixes updates the create-big.test to match the new
behavior.