[TFMarian] Slow integration tests are failing
Author: patrickvonplaten
Pull request: no

After having uploaded the TF weights of: 
- https://huggingface.co/Helsinki-NLP/opus-mt-mt-en/commit/552db365bf294f7a2604fadcedfca0ed5b29bd66
- https://huggingface.co/Helsinki-NLP/opus-mt-en-zh/commit/137ef1a50f7a0eaf22a7d5685d07b66bb670ddd1
- https://huggingface.co/Helsinki-NLP/opus-mt-en-ROMANCE/commit/1854185e5a3183d8c73360b1cd53f63c2fb0ed46

and merged this PR: 

https://github.com/huggingface/transformers/pull/10664

the TFMarian slow integration tests are falling. This doesn't seem to be an easy issue and needs further investigation.

cc @patrickvonplaten @patil-suraj 

Comments:
This is a very weird bug actually and can be reproduced the easiest ass follows:

```python
#!/usr/bin/env python3
from transformers import TFMarianMTModel, MarianMTModel, MarianTokenizer

tokenizer = MarianTokenizer.from_pretrained("Helsinki-NLP/opus-mt-mt-en")

model_pt = MarianMTModel.from_pretrained("Helsinki-NLP/opus-mt-mt-en")
model_tf = TFMarianMTModel.from_pretrained("Helsinki-NLP/opus-mt-mt-en", from_pt=True)

model_tf.save_pretrained("./")
model_tf = TFMarianMTModel.from_pretrained("./")

input_str = "My name is Wolfgang and I live in Berlin"
input_str = "Billi messu b'mod ġentili, Ġesù fejjaq raġel li kien milqut bil - marda kerha tal - ġdiem."


output_tokens_pt = model_pt.generate(tokenizer(input_str, return_tensors="pt").input_ids)
output_tokens_tf = model_tf.generate(tokenizer(input_str, return_tensors="tf").input_ids)

print("Pt:", tokenizer.batch_decode(output_tokens_pt))
print("Tf:", tokenizer.batch_decode(output_tokens_tf))
```

fails while commenting out the save and load lines works:

```python
#!/usr/bin/env python3
from transformers import TFMarianMTModel, MarianMTModel, MarianTokenizer

tokenizer = MarianTokenizer.from_pretrained("Helsinki-NLP/opus-mt-mt-en")

model_pt = MarianMTModel.from_pretrained("Helsinki-NLP/opus-mt-mt-en")
model_tf = TFMarianMTModel.from_pretrained("Helsinki-NLP/opus-mt-mt-en", from_pt=True)

input_str = "My name is Wolfgang and I live in Berlin"
input_str = "Billi messu b'mod ġentili, Ġesù fejjaq raġel li kien milqut bil - marda kerha tal - ġdiem."


output_tokens_pt = model_pt.generate(tokenizer(input_str, return_tensors="pt").input_ids)
output_tokens_tf = model_tf.generate(tokenizer(input_str, return_tensors="tf").input_ids)

print("Pt:", tokenizer.batch_decode(output_tokens_pt))
print("Tf:", tokenizer.batch_decode(output_tokens_tf))
```

Most other TFMarian models work correctly. This is pretty weird though and will need more time for investigation (cc @patil-suraj for info)

Thanks for your investigation!

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