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/passthrough/doc_template.md

@@ -1,35 +0,0 @@
----
-orphan: true
----
-# Passthrough Distribution
-
-```{toctree}
-:maxdepth: 2
-:hidden:
-
-self
-```
-
-The `llamastack/distribution-{{ name }}` distribution consists of the following provider configurations.
-
-{{ providers_table }}
-
-{% if run_config_env_vars %}
-### Environment Variables
-
-The following environment variables can be configured:
-
-{% for var, (default_value, description) in run_config_env_vars.items() %}
-- `{{ var }}`: {{ description }} (default: `{{ default_value }}`)
-{% endfor %}
-{% endif %}
-
-{% if default_models %}
-### Models
-
-The following models are available by default:
-
-{% for model in default_models %}
-- `{{ model.model_id }} {{ model.doc_string }}`
-{% endfor %}
-{% endif %}