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/distribution/providers.py

@@ -84,7 +84,13 @@ class ProviderImpl(Providers):
                 Each API maps to a dictionary of provider IDs to their health responses.
         """
         providers_health: dict[str, dict[str, HealthResponse]] = {}
-        timeout = 1.0
+
+        # The timeout has to be long enough to allow all the providers to be checked, especially in
+        # the case of the inference router health check since it checks all registered inference
+        # providers.
+        # The timeout must not be equal to the one set by health method for a given implementation,
+        # otherwise we will miss some providers.
+        timeout = 3.0
 
         async def check_provider_health(impl: Any) -> tuple[str, HealthResponse] | None:
             # Skip special implementations (inspect/providers) that don't have provider specs