Use new soong support to install privapp xml

This allows better overriding of it in the variants of this apex
that have a different package name.

Bug: 242509786
Test: build google tethering, diff before & after
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:91442c93fb8d7f67bf90faab0552428ff07f0452)
Merged-In: I84c53458686f70408ec759df854f5fcdee9cdaed
Change-Id: I84c53458686f70408ec759df854f5fcdee9cdaed
diff --git a/Tethering/Android.bp b/Tethering/Android.bp
index 23ce1a4..4478b1e 100644
--- a/Tethering/Android.bp
+++ b/Tethering/Android.bp
@@ -195,7 +195,7 @@
     certificate: "networkstack",
     manifest: "AndroidManifest.xml",
     use_embedded_native_libs: true,
-    required: ["privapp_allowlist_com.android.tethering"],
+    privapp_allowlist: ":privapp_allowlist_com.android.tethering",
     apex_available: ["com.android.tethering"],
     lint: { strict_updatability_linting: true },
 }
@@ -211,7 +211,7 @@
     certificate: "networkstack",
     manifest: "AndroidManifest.xml",
     use_embedded_native_libs: true,
-    required: ["privapp_allowlist_com.android.tethering"],
+    privapp_allowlist: ":privapp_allowlist_com.android.tethering",
     apex_available: ["com.android.tethering"],
     lint: { strict_updatability_linting: true },
 }