Add visibility for TetheringCoverageTests

1. NetworkStackTestsLib can be visible to TetheringCoverageTests
2. NetworkStackJarJarRules can be visible to
   TetheringIntegrationTestsDefaults
3. Remove uncessary lib "libartbase" because
   it's not visible to TetheringCoverageTests.

Bug: 148636687
Test: atest NetworkStackTests
      atest TetheringCoverageTests
Change-Id: I0e0d597a968f99f4a99c3d7ab014af4e144ab40f
Merged-In: I0e0d597a968f99f4a99c3d7ab014af4e144ab40f
(cherry picked from commit 7a95e2e5e9cffbf7cdb67d75306c6bfd2ebc4663)
diff --git a/Android.bp b/Android.bp
index 6dd4ca2..ff66af4 100644
--- a/Android.bp
+++ b/Android.bp
@@ -139,6 +139,7 @@
     visibility: [
         "//packages/modules/NetworkStack/tests/unit",
         "//packages/modules/NetworkStack/tests/integration",
+        "//frameworks/base/packages/Tethering/tests/integration",
     ]
 }