fix: store configs (#2593)

# What does this PR do?
https://github.com/meta-llama/llama-stack/pull/2490 broke postgres_demo,
as the config expected a str but the value was converted to int.

This PR:
1. Updates the type of port in sqlstore to be int
2. template generation uses `dict` instead of `StackRunConfig` so as to
avoid failing pydantic typechecks.
3. Adds `replace_env_vars` to StackRunConfig instantiation in
`configure.py` (not sure why this wasn't needed before).

## Test Plan
`llama stack build --template postgres_demo --image-type conda --run`

llama_stack/templates/starter/starter.py

@@ -234,7 +234,6 @@ def get_distribution_template() -> DistributionTemplate:
 
     default_models = get_model_registry(available_models)
 
-    postgres_store = PostgresSqlStoreConfig.sample_run_config()
     return DistributionTemplate(
         name=name,
         distro_type="self_hosted",
@@ -243,7 +242,7 @@ def get_distribution_template() -> DistributionTemplate:
         template_path=None,
         providers=providers,
         available_models_by_provider=available_models,
-        additional_pip_packages=postgres_store.pip_packages,
+        additional_pip_packages=PostgresSqlStoreConfig.pip_packages(),
         run_configs={
             "run.yaml": RunConfigSettings(
                 provider_overrides={