feat: consolidate most distros into "starter" (#2516)

# What does this PR do?

* Removes a bunch of distros
* Removed distros were added into the "starter" distribution
* Doc for "starter" has been added
* Partially reverts https://github.com/meta-llama/llama-stack/pull/2482
  since inference providers are disabled by default and can be turned on
  manually via env variable.
* Disables safety in starter distro

Closes: https://github.com/meta-llama/llama-stack/issues/2502.

~Needs: https://github.com/meta-llama/llama-stack/pull/2482 for Ollama
to work properly in the CI.~

TODO:

- [ ] We can only update `install.sh` when we get a new release.
- [x] Update providers documentation
- [ ] Update notebooks to reference starter instead of ollama

Signed-off-by: Sébastien Han <seb@redhat.com>

tests/integration/inference/test_openai_completion.py

@@ -45,7 +45,7 @@ def skip_if_model_doesnt_support_suffix(client_with_models, model_id):
     # To test `fim` ( fill in the middle ) completion, we need to use a model that supports suffix.
     # Use this to specifically test this API functionality.
 
-    # pytest -sv --stack-config="inference=ollama" \
+    # pytest -sv --stack-config="inference=starter" \
     # tests/integration/inference/test_openai_completion.py \
     # --text-model qwen2.5-coder:1.5b \
     # -k test_openai_completion_non_streaming_suffix