fix(tests): add missing GCP provider step definition

Added @then('the resource should have provider "gcp"') step that corresponds to the 'Then the resource should have provider gcp' scenario in cloud_types.feature. This fix eliminates the MissingStep error causing unit_tests CI failure.

Resolves Review #8104 Blocker A identified by pr-review-worker.

ISSUES CLOSED: #8607

features/resource/cloud_types_steps.py

@@ -209,6 +209,13 @@ def step_azure_subscription_id_lowercase(context):
         context.exc = exc
 
 
+@then('the resource should have provider "gcp"')
+def step_resource_provider_is_gcp(context):
+    """Assert the constructed resource has provider 'gcp'."""
+    assert context.exc is None
+    assert context.result.provider == "gcp"
+
+
 @then('the resource should have provider "azure"')
 def step_azure_provider_is_azure(context):
     """Assert AzureResource has provider 'azure'."""