Turn USE_SOONG_UI on by default

Set USE_SOONG_UI=false to disable the new soong_ui wrapper.

Test: m -j blueprint_tools
Test: USE_SOONG_UI=false m -j blueprint_tools
Change-Id: I0b217939a29fd51e69ef594f824b14e25a4c8c4d
diff --git a/core/main.mk b/core/main.mk
index 85f5d6c..739fc11 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -10,7 +10,7 @@
 endif
 
 ifndef KATI
-USE_SOONG_UI ?= false
+USE_SOONG_UI ?= true
 endif
 ifeq ($(USE_SOONG_UI),true)