feat(oauth/oidc): move token exchange from beta to GA (#11475)

# Which Problems Are Solved

This PR marks the OAuth2 Token Exchange as general available (GA).

# How the Problems Are Solved

- API:
- deprecated the feature toggle (to prevent breaking changes) in v2beta
and v2 API
- removed all related event logic and updated the projection interation
  - removed the toggle usage for token exchange
  - removed related translations
- Management Console:
  - removed the feature toggle and its translations
- Docs:
  - removed all beta labels and feature toggle notes

# Additional Changes

- removed unused `Errors.WebKey.FeatureDisabled` translations

# Additional Context

- closes #11114

---------

Co-authored-by: Marco A. <[email protected]>

internal/query/system_features_model.go

@@ -57,7 +57,6 @@ func (m *SystemFeaturesReadModel) Query() *eventstore.SearchQueryBuilder {
 			feature_v2.SystemResetEventType,
 			feature_v2.SystemLoginDefaultOrgEventType,
 			feature_v2.SystemUserSchemaEventType,
-			feature_v2.SystemTokenExchangeEventType,
 			feature_v2.SystemImprovedPerformanceEventType,
 			feature_v2.SystemOIDCSingleV1SessionTerminationEventType,
 			feature_v2.SystemEnableBackChannelLogout,
@@ -85,8 +84,6 @@ func reduceSystemFeatureSet[T any](features *SystemFeatures, event *feature_v2.S
 		features.LoginDefaultOrg.set(level, event.Value)
 	case feature.KeyUserSchema:
 		features.UserSchema.set(level, event.Value)
-	case feature.KeyTokenExchange:
-		features.TokenExchange.set(level, event.Value)
 	case feature.KeyImprovedPerformance:
 		features.ImprovedPerformance.set(level, event.Value)
 	case feature.KeyOIDCSingleV1SessionTermination: