PixelPaint: Remove conflicting action hotkey

The new CommandPalette feature conflicts with PixelPaint's Clear
Selection action keyboard shortcut (Ctrl + Shift + A).

Fixes: #12222

Userland/Applications/PixelPaint/MainWidget.cpp

@@ -282,7 +282,7 @@ void MainWidget::initialize_menubar(GUI::Window& window)
         editor->selection().merge(editor->active_layer()->relative_rect(), PixelPaint::Selection::MergeMode::Set);
     }));
     m_edit_menu->add_action(GUI::Action::create(
-        "Clear &Selection", { Mod_Ctrl | Mod_Shift, Key_A }, Gfx::Bitmap::try_load_from_file("/res/icons/16x16/clear-selection.png").release_value_but_fixme_should_propagate_errors(), [&](auto&) {
+        "Clear &Selection", Gfx::Bitmap::try_load_from_file("/res/icons/16x16/clear-selection.png").release_value_but_fixme_should_propagate_errors(), [&](auto&) {
             auto* editor = current_image_editor();
             VERIFY(editor);
             editor->selection().clear();