Add shared jarjar rule for tethering tests

Also jarjar com.android.net.module.util* to
com.android.networkstack.tethering.util*.

Bug: 171670016
Test: atest TetheringCoverageTests
Change-Id: I3bde9ad3c41adf36da99bd944303d88ce992201c
diff --git a/Tethering/tests/unit/Android.bp b/Tethering/tests/unit/Android.bp
index 45c7b65..3589725 100644
--- a/Tethering/tests/unit/Android.bp
+++ b/Tethering/tests/unit/Android.bp
@@ -67,7 +67,6 @@
         "libdexmakerjvmtiagent",
         "libstaticjvmtiagent",
     ],
-    jarjar_rules: "jarjar-rules.txt",
 }
 
 // Library containing the unit tests. This is used by the coverage test target to pull in the
@@ -88,6 +87,7 @@
         "device-tests",
         "mts",
     ],
+    jarjar_rules: ":TetheringTestsJarJarRules",
     defaults: ["TetheringTestsDefaults"],
     compile_multilib: "both",
 }