Make service-connectivity APEX-only

service-connectivity is not used by arc-services anymore, so it does not
need apex_available for the platform anymore.

Bug: 183691942
Test: m
Change-Id: I8e7aa59e517a3694b7c4c1ed1e29f4281777b62c
diff --git a/service/Android.bp b/service/Android.bp
index 518f198..20ccf06 100644
--- a/service/Android.bp
+++ b/service/Android.bp
@@ -113,7 +113,6 @@
     ],
     jarjar_rules: "jarjar-rules.txt",
     apex_available: [
-        "//apex_available:platform", // For arc-services
         "com.android.tethering",
     ],
 }