Handle display driver preferences consistently between editor and projects

[Riteo]

The way that it was implemented before allowed for the project property to spill over to the editor if the prefer_wayland property is not present which, while not completely likely, is still a possibility. This specific part is thus more of a correctness change, ensuring that we always enforce the default display server when not running a project.

This commit also removes the restart requirement for the relative display driver project settings as they're independent and a restart would do nothing useful.

[akien-mga]

Thanks!

[mihe]

@akien-mga This resulted in a regression it seems: #94755

[Riteo]

ok all right, stared at it for a solid minute and remembered why stuff is the way it is.

Basically, since projects can run with wayland and project settings carry over into the editor, if prefer_wayland is not found, it will still run as wayland instead of whatever was the default.

I'm quite sure that the proper solution here is checking for an empty display_setting before setting anything, like this:

diff --git a/main/main.cpp b/main/main.cpp
index e1d53e7f1b..059172b14e 100644
--- a/main/main.cpp
+++ b/main/main.cpp
@@ -2631,10 +2631,12 @@ Error Main::setup2(bool p_show_boot_logo) {
                                                }
                                        }
 
-                                       if (prefer_wayland) {
-                                               display_driver = "wayland";
-                                       } else {
-                                               display_driver = "default";
+                                       if (display_driver.is_empty()) {
+                                               if (prefer_wayland) {
+                                                       display_driver = "wayland";
+                                               } else {
+                                                       display_driver = "default";
+                                               }
                                        }
                                }
                        }

I'll test it further and if that's indeed the solution I'll make a PR ASAP, sorry for the inconvenience.