oidc: Remove "aud" claim validation of logout tokens (#6156)

The "aud" claim of the logout token is supposed to contain the client-id
of the client for which the token was issued. Our current implementation of
validating that claim is somewhat broken. We only allow to configure a single
value for the allowed client id. But we have different client-ids
accessing oCIS.

This completely removes the current validation of the `aud` claim until
we come up with a working solution. As we currently require a session id
to be present in the logout token the risk not validating the `aud`
claim is pretty low.

Related: #6149

ocis-pkg/oidc/options.go

@@ -27,11 +27,6 @@ type Options struct {
 	// AccessTokenVerifyMethod to use when verifying access tokens
 	// TODO pass a function or interface to verify? an AccessTokenVerifier?
 	AccessTokenVerifyMethod string
-	// ClientID the client id to expect in tokens. If not set SkipClientIDCheck must be true
-	// TODO also check in access token
-	ClientID string
-	// SkipClientIDCheck must be true if ClientID is empty
-	SkipClientIDCheck bool
 	// Config to use
 	Config *goidc.Config
 
@@ -92,20 +87,6 @@ func WithKeySet(val KeySet) Option {
 	}
 }
 
-// WithClientID provides a function to set the clientID option.
-func WithClientID(val string) Option {
-	return func(o *Options) {
-		o.ClientID = val
-	}
-}
-
-// WithSkipClientIDCheck provides a function to set the skipClientIDCheck option.
-func WithSkipClientIDCheck(val bool) Option {
-	return func(o *Options) {
-		o.SkipClientIDCheck = val
-	}
-}
-
 // WithConfig provides a function to set the Config option.
 func WithConfig(val *goidc.Config) Option {
 	return func(o *Options) {