Fix mypy no-redef error for result variable in decision_service

Remove duplicate type annotation on second assignment to `result`,
which was already typed on line 805.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: FarhanAnjum-opti

optimizely/decision_service.py

@@ -851,7 +851,7 @@ def get_decision_for_flag(
                         decision = Decision(experiment, variation_result['variation'],
                                             enums.DecisionSources.FEATURE_TEST,
                                             variation_result['cmab_uuid'])
-                        result: DecisionResult = {
+                        result = {
                             'decision': decision,
                             'error': False,
                             'reasons': reasons