Big TF test cleanup
Now we've done a big overhaul of the TF model internals, a lot of tests can be fixed. Several tests were disabled for being buggy or too slow - these are almost all performant now, so I re-enabled them. Runtime for the re-enabled tests was 15-20 seconds on my local machine.

Also, we had a number of TF test failures in the daily CI. I think this PR should fix all of them, except for two cases:

Firstly, some models have issues with `resize_token_embeddings`. These failures are caused by the transition to `TFSharedEmbedding` that @gante is currently working on, and I didn't want to interfere! The usual cause is that `resize_token_embeddings` replaces the new-style `TFSharedEmbedding` with an old `tf.Variable`.

Secondly, there are a couple of failures in generate tests. I'm also leaving this to @gante because he knows much more about that code than me :sweat_smile: 
_The documentation is not available anymore as the PR was closed or merged._<|||||>(@Rocketknight1 ping me if the gen tests are not sorted after the latest push)<|||||>I think everything has been addressed now, but I'm not going to merge this one today because there's another PR affecting our tests (#24301) and ideally I'd like to be able to separately view their impact on the CI!<|||||>> I think everything has been addressed now, but I'm not going to merge this one today

Nice 👍 .

I never merge PRs on Firday evening or early afternoon. I don't want to get a ☎️ ⚡ !<|||||>Wait, you merged ...!? (but you said you are not going to merge 🤔 )