Set updateable:false explicitly in apex rules.

Currently, this is the default so this is a no-op,
But the default is changing to true.

Bug: 180375550
Test: Treehugger
Change-Id: Ib841e474ab2b2ff2b54c160bb06c3bbbeea92675
diff --git a/Tethering/apex/Android.bp b/Tethering/apex/Android.bp
index 7970944..acb87bf 100644
--- a/Tethering/apex/Android.bp
+++ b/Tethering/apex/Android.bp
@@ -18,7 +18,7 @@
     name: "com.android.tethering",
     // TODO: make updatable again once this contains only updatable artifacts (in particular, this
     // cannot build as updatable unless service-connectivity builds against stable API).
-    // updatable: true,
+    updatable: false,
     // min_sdk_version: "30",
     java_libs: [
         "framework-tethering",