Remove support for '--force-grab-cursor' in GameScope

This option is undocumented, may not be supported in current GameScope, nobody seems to understand what it does very clearly, and can be activated via the custom flags for GameScope anyway.

lutris/runner_interpreter.py

@@ -112,8 +112,6 @@ def get_launch_parameters(runner, gameplay_info):
 def get_gamescope_args(launch_arguments, system_config):
     """Insert gamescope at the start of the launch arguments"""
     launch_arguments.insert(0, "--")
-    if system_config.get("gamescope_force_grab_cursor"):
-        launch_arguments.insert(0, "--force-grab-cursor")
     if system_config.get("gamescope_fsr_sharpness"):
         gamescope_fsr_sharpness = system_config["gamescope_fsr_sharpness"]
         launch_arguments.insert(0, gamescope_fsr_sharpness)

lutris/sysoptions.py

@@ -149,17 +149,6 @@ system_options = [  # pylint: disable=invalid-name
         "help": _("Use gamescope to draw the game window isolated from your desktop.\n"
                   "Toggle fullscreen: Super + F"),
     },
-    {
-        "section": "Gamescope",
-        "option": "gamescope_force_grab_cursor",
-        "type": "bool",
-        "label": _("Relative Mouse Mode"),
-        "advanced": True,
-        "default": False,
-        "condition": bool(system.find_executable("gamescope")),
-        "help": _("Always use relative mouse mode instead of flipping\n"
-                  "dependent on cursor visibility"),
-    },
     {
         "section": "Gamescope",
         "option": "gamescope_output_res",