Remove apk_under_test dependency from proguard

This is partial revert of
https://chromium-review.googlesource.com/1082010

This improves build parallelism and remove around 5 mins from compile step on android builders in some cases.

Bug: 848494
Change-Id: I2d51decd25125e3cfb3e036e142925dfe9358512
Reviewed-on: https://chromium-review.googlesource.com/1121670
Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
Reviewed-by: agrieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/master@{#572461}

build/config/android/rules.gni

@@ -2462,10 +2462,6 @@ if (enable_java_templates) {
             "--proguard-config-exclusions=$_rebased_proguard_config_exclusions",
           ]
         }
-        if (defined(invoker.apk_under_test)) {
-          args += [ "--mapping=@FileArg($_rebased_build_config:deps_info:proguard_under_test_mapping)" ]
-          deps += [ "${invoker.apk_under_test}__proguard" ]
-        }
       }
       _dex_sources = [ _proguard_output_jar_path ]
       _dex_deps = [ ":$_proguard_target" ]