Remove more internal fields from ModuleBase.

Bug: 358425833
Test: Manual compare the generated ninja and mk files and CI.
Change-Id: I4edd0dc646ac035594f47cd9044cc4eb5f710e64
diff --git a/android/module_context.go b/android/module_context.go
index 253bebd..f619da2 100644
--- a/android/module_context.go
+++ b/android/module_context.go
@@ -231,8 +231,8 @@
 	module          Module
 	phonies         map[string]Paths
 
-	katiInstalls []katiInstall
-	katiSymlinks []katiInstall
+	katiInstalls katiInstalls
+	katiSymlinks katiInstalls
 
 	testData []DataPath