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/projection/system_features.go

@@ -12,7 +12,7 @@ import (
 )
 
 const (
-	SystemFeatureTable = "projections.system_features2"
+	SystemFeatureTable = "projections.system_features3"
 
 	SystemFeatureKeyCol          = "key"
 	SystemFeatureCreationDateCol = "creation_date"
@@ -60,10 +60,6 @@ func (*systemFeatureProjection) Reducers() []handler.AggregateReducer {
 				Event:  feature_v2.SystemUserSchemaEventType,
 				Reduce: reduceSystemSetFeature[bool],
 			},
-			{
-				Event:  feature_v2.SystemTokenExchangeEventType,
-				Reduce: reduceSystemSetFeature[bool],
-			},
 			{
 				Event:  feature_v2.SystemImprovedPerformanceEventType,
 				Reduce: reduceSystemSetFeature[[]feature.ImprovedPerformanceType],