appearance: Remove useless match_wm_manager_init function

[zhuyaliang]

appearance is no need to call match_wm_manager_init because we no longer use match_wm_manager_get_current and match_wm_manager_spawn_config_tool_for_current, This is a useless initialization Similarly, libwindow-settings is an outdated and unnecessary API that has not been called by any project

[raveit65]

I am still wondering when mate_wm_manager_get_current and mate_wm_manager_spawn_config_tool were used. Currently we definitely don't use them.

[raveit65]

Btw. I guess you meant mate_wm_manager_get_current, mate_wm_manager_spawn_config_tool and mate_wm_manager_init. Looks like a typo or not? Can you rename commit message please?