Refactor Lambda dimensions into helper method to reduce branches

Extract Lambda dimension logic into _add_lambda_dimensions() method
to reduce the number of branches in _create_emf_log() from 13 to 12,
fixing the pylint too-many-branches error.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <[email protected]>

Author: syed-ahsan-ishtiaque

aws-opentelemetry-distro/src/amazon/opentelemetry/distro/exporter/aws/metrics/base_emf_exporter.py

@@ -191,6 +191,30 @@ def _get_dimension_names(self, attributes: Attributes) -> List[str]:
         # For now, use all attributes as dimensions
         return list(attributes.keys())
 
+    def _add_lambda_dimensions(
+        self, emf_log: Dict, dimension_names: List[str], resource: Resource
+    ) -> List[str]:
+        """
+        Add Service and Environment dimensions for Lambda environments.
+
+        Args:
+            emf_log: The EMF log dictionary to add dimension values to
+            dimension_names: The current list of dimension names
+            resource: The OTel Resource to extract service name from
+
+        Returns:
+            Updated list of dimension names with Service and Environment prepended (if Lambda)
+        """
+        if not self._is_lambda:
+            return dimension_names
+
+        service_name, _ = get_service_attribute(resource) if resource else ("UnknownService", True)
+        # Add dimension values to the EMF log root
+        emf_log["Service"] = service_name
+        emf_log["Environment"] = LAMBDA_ENVIRONMENT_DEFAULT
+        # Add Service and Environment to dimension names (at the beginning for consistency)
+        return ["Service", "Environment"] + dimension_names
+
     def _get_attributes_key(self, attributes: Attributes) -> str:
         """
         Create a hashable key from attributes for grouping metrics.
@@ -501,13 +525,7 @@ def _create_emf_log(
             emf_log[name] = str(value)
 
         # Add Service and Environment dimensions for Lambda
-        if self._is_lambda:
-            service_name, _ = get_service_attribute(resource) if resource else ("UnknownService", True)
-            # Add Service and Environment to dimension names (at the beginning for consistency)
-            dimension_names = ["Service", "Environment"] + dimension_names
-            # Add dimension values to the EMF log root
-            emf_log["Service"] = service_name
-            emf_log["Environment"] = LAMBDA_ENVIRONMENT_DEFAULT
+        dimension_names = self._add_lambda_dimensions(emf_log, dimension_names, resource)
 
         # Add CloudWatch Metrics if we have metrics, include dimensions only if they exist
         if metric_definitions: