TPU tests fail silently in CI

[akihironitta]

Oh no, we have a test failure and it doesn't surface (from master) 😭
Did I mess something up in #11098?
This is so strange, back then, all test errors would always result in a failed CI signal.

Originally posted by @awaelchli in #14013 (comment)

cc @carmocca @akihironitta @Borda @kaushikb11 @rohitgr7

[akihironitta]

@awaelchli I completely missed it! Thank you for pointing it out and opening #14034! I will also try to contribute to this issue!