Add a skipif for this test with --fast, it relies on bounds checking

[lydia-duncan]

Passed a fresh checkout of the test with and without --fast

[bradcray]

An alternate technique that we've been trying to use for cases like this is to add a compopts with --checks in it so that the test is checking what it's designed to regardless of how it's run (including a user-supplied -compopts flag on their start_test run like --compopts --no-checks).

(even when using a skipif for cases like this, I always suggest reaching for a suppressif instead so that if the test suddenly starts passing in fast testing, we learn that --fast isn't turning off bounds checking anymore).