[net] use link_deps for reporting_policy_proto

I will deprecate deps in proto_library for improved build throughput.
And we can use link_deps here instead.

Bug: 938011
Change-Id: I03b3004c549986f302b36142dbf5dc2974bf9631
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1504482
Auto-Submit: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Matt Menke <mmenke@chromium.org>
Reviewed-by: Matt Menke <mmenke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#638155}

net/BUILD.gn

@@ -6402,9 +6402,7 @@ proto_library("reporting_policy_proto") {
   sources = [
     "reporting/reporting_policy.proto",
   ]
-  deps = [
-    "//testing/libfuzzer/proto:json_proto",
-  ]
+  link_deps = [ "//testing/libfuzzer/proto:json_proto" ]
 }
 
 fuzzer_test("net_reporting_header_parser_fuzzer") {