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>

llama_stack/templates/nvidia/build.yaml

@@ -1,29 +0,0 @@
-version: 2
-distribution_spec:
-  description: Use NVIDIA NIM for running LLM inference, evaluation and safety
-  providers:
-    inference:
-    - remote::nvidia
-    vector_io:
-    - inline::faiss
-    safety:
-    - remote::nvidia
-    agents:
-    - inline::meta-reference
-    telemetry:
-    - inline::meta-reference
-    eval:
-    - remote::nvidia
-    post_training:
-    - remote::nvidia
-    datasetio:
-    - inline::localfs
-    - remote::nvidia
-    scoring:
-    - inline::basic
-    tool_runtime:
-    - inline::rag-runtime
-image_type: conda
-additional_pip_packages:
-- aiosqlite
-- sqlalchemy[asyncio]