fix: use project initial_value for control in identity override

When editing an identity override for a multivariate feature, the
control value was incorrectly showing the identity's selected
variation value instead of the project's actual control value.

This caused the selected variation to appear twice in the list -
once as "control" and once in the variations list.

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Author: talissoncosta

frontend/web/components/modals/create-feature/tabs/FeatureValue.tsx

@@ -236,7 +236,7 @@ const FeatureValue: FC<EditFeatureValueProps> = ({
                 <VariationOptions
                   disabled
                   select
-                  controlValue={featureState.feature_state_value}
+                  controlValue={projectFlag.initial_value}
                   controlPercentage={controlPercentage}
                   variationOverrides={identityVariations}
                   setVariations={(multivariate_feature_state_values) =>