Fix build warnings for CaptivePortalLogin

CaptivePortalLogin needs only the defintion in
metrics_constants.proto. This will not need the jarjar_rules.
Thus, remove the unnecessary rule to fix the build warning.

Test: make CaptivePortalLogin and no warning
Bug: 123717273
Change-Id: I5bb3ee61be769989d02a2762a7747d4dafd7bd71

proto/Android.bp

@@ -27,14 +27,4 @@ java_library_static {
     srcs: ["src/metrics_constants.proto"],
     no_framework_libs: true,
     sdk_version: "system_current",
-    // Pin java_version until jarjar is certified to support later versions. http://b/72703434
-    java_version: "1.8",
-    target: {
-        android: {
-            jarjar_rules: "jarjar-rules.txt",
-        },
-        host: {
-            static_libs: ["libprotobuf-java-nano"],
-        },
-    },
 }