proto: change username of UP cred to be sensitive (#5934)

* proto: change username of UP cred to be sensitive

internal/proto/controller/api/resources/sessionrecordings/v1/session_recording.proto

@@ -314,7 +314,7 @@ message Credential {
 // The attributes of a UsernamePassword Credential.
 message UsernamePasswordCredentialAttributes {
   // The username associated with the credential.
-  string username = 1; // @gotags: class:"public"
+  string username = 1; // @gotags: class:"sensitive"
 
   // The hmac value of the password.
   string password_hmac = 2; // @gotags: class:"public"