Non-pixel systemui should also have a separate shell thread

Shell thread should be stable now and is required for slower
devices where systemui eats-up most of the looper time.

Bug: 253378401
Test: tests using aosp sysui (eg. avd_boot_test)
Change-Id: Ia158dd7e005ec3534925d07db1ebfe1b5b3d0d6b
diff --git a/packages/SystemUI/res/values/config.xml b/packages/SystemUI/res/values/config.xml
index 88af179..8791389 100644
--- a/packages/SystemUI/res/values/config.xml
+++ b/packages/SystemUI/res/values/config.xml
@@ -285,6 +285,9 @@
     <!-- Whether to show the full screen user switcher. -->
     <bool name="config_enableFullscreenUserSwitcher">false</bool>
 
+    <!-- Determines whether the shell features all run on another thread. -->
+    <bool name="config_enableShellMainThread">true</bool>
+
     <!-- SystemUIFactory component -->
     <string name="config_systemUIFactoryComponent" translatable="false">com.android.systemui.SystemUIInitializerImpl</string>