Enable code shrinking (dead code removal) on Launcher3QuickStepGo app

Bug: 112042795
Test: Manual testing

I found following effect of shrinking on the apk:

Launcher3QuickStepGo.apk            4925099 bytes
Launcher3QuickStepGo_Proguard.apk   2619051 bytes

We get total saving of 2306048 bytes in apk size.

Change-Id: I75abedc05e5d04967928e73f02bcc78608f52ac0
diff --git a/Android.mk b/Android.mk
index 3945746..3bda309 100644
--- a/Android.mk
+++ b/Android.mk
@@ -193,7 +193,7 @@
     $(LOCAL_PATH)/quickstep/res \
     $(LOCAL_PATH)/go/res
 
-LOCAL_PROGUARD_ENABLED := disabled
+LOCAL_PROGUARD_ENABLED := full
 
 LOCAL_SDK_VERSION := system_current
 LOCAL_MIN_SDK_VERSION := 26