fix: Fix unit tests CI and failing tests (#2928)

# What does this PR do?
<!-- Provide a short summary of what this PR does and why. Link to
relevant issues if applicable. -->
- Added `set -e` to the beginning of the unit test script to ensure the
script exits on failure and correctly fails the CI when tests do not
pass.
- Fixed all unit tests that were silently failing in the CI.
- Fixed Python 3.13 unit test CI failing silently.

<!-- If resolving an issue, uncomment and update the line below -->
<!-- Closes #[issue-number] -->
Closes #2877 

## Test Plan
<!-- Describe the tests you ran to verify your changes with result
summaries. *Provide clear instructions so the plan can be easily
re-executed.* -->
- **Previously:** Unit tests passing in CI eventhough it failed 11 tests
->
[CI-run](4683681501 (step):4:2097)
- **Made the fix. Now, ensuring CI fails as expected on test failures:**
Unit tests failing in CI with 1 failed test ->
[CI-run](4684234247 (step):4:1506)
- This PR shows the CI passing and all unit tests passing.

tests/unit/distribution/test_distribution.py

@@ -346,7 +346,7 @@ pip_packages:
 
     def test_external_provider_from_module_building(self, mock_providers):
         """Test loading an external provider from a module during build (building=True, partial spec)."""
-        from llama_stack.distribution.datatypes import BuildConfig, DistributionSpec, Provider
+        from llama_stack.distribution.datatypes import BuildConfig, BuildProvider, DistributionSpec
         from llama_stack.providers.datatypes import Api
 
         # No importlib patch needed, should not import module when type of `config` is BuildConfig or DistributionSpec
@@ -358,10 +358,8 @@ pip_packages:
                 description="test",
                 providers={
                     "inference": [
-                        Provider(
-                            provider_id="external_test",
+                        BuildProvider(
                             provider_type="external_test",
-                            config={},
                             module="external_test",
                         )
                     ]