Revert of Make separate net and url GN targets with and without ICU (…

…patchset chromium#8 id:300001 of https://codereview.chromium.org/1287893005/ )

Reason for revert:
This CL broke a GN check on an internal bot:
https://uberchromegw.corp.google.com/i/chromium.linux/builders/Android%20GN/builds/29756

Running ['/b/build/slave/Android_GN/build/src/buildtools/linux64/gn', '--root=/b/build/slave/Android_GN/build/src', 'check', '//out/Release']
ERROR at //url/android/url_jni_registrar.cc:8:11: Include not allowed.
#include "url/url_canon_icu_alternatives_android.h"
          ^---------------------------------------
It is not in any dependency of
  //url:url
The include file is in the target(s):
  //url:url_lib_use_icu_alternatives_on_android
which should somehow be reachable.
Command ['/b/build/slave/Android_GN/build/src/buildtools/linux64/gn', '--root=/b/build/slave/Android_GN/build/src', 'check', '//out/Release'] returned exit code 1

Original issue's description:
> Make separate net and url GN targets with and without ICU
>
> The net and url GYP files were modified in crrev.com/933293003
> so Cronet could be built side-by-side with Chrome. However GN
> files are not modified. This CL keeps the GN files in sync
> with the GYP files.
>
> BUG=522096
>
> Committed: https://crrev.com/4c8c6921ca6739d16f6551635328faf164848f9d
> Cr-Commit-Position: refs/heads/master@{#345891}

TBR=mmenke@chromium.org,brettw@chromium.org
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=522096

Review URL: https://codereview.chromium.org/1312583006

Cr-Commit-Position: refs/heads/master@{#345906}