feat(conda): share envs with transformer-based backends (#1465)

* feat(conda): share env between diffusers and bark

* Detect if env already exists

* share diffusers and petals

* tests: add petals

* Use smaller model for tests with petals

* test only model load on petals

* tests(petals): run only load model tests

* Revert "test only model load on petals"

This reverts commit 111cfa97f1.

* move transformers and sentencetransformers to common env

* Share also transformers-musicgen

backend/python/diffusers/diffusers.yml

@@ -70,4 +70,4 @@ dependencies:
       - typing-extensions==4.8.0
       - urllib3==2.0.6
       - zipp==3.17.0
-prefix: /opt/conda/envs/diffusers
+prefix: /opt/conda/envs/diffusers