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/command/instance_features_test.go

@@ -335,13 +335,6 @@ func TestInstanceFeatures_isEmpty(t *testing.T) {
 			},
 			want: false,
 		},
-		{
-			name: "TokenExchange set",
-			features: &InstanceFeatures{
-				TokenExchange: gu.Ptr(true),
-			},
-			want: false,
-		},
 		{
 			name: "ImprovedPerformance set",
 			features: &InstanceFeatures{