Revert of Creating webrtc/modules:module_api (patchset #5 id:80001 of https://codereview.webrtc.org/2838873002/ )

Reason for revert:
Causes build problem: https://build.chromium.org/p/client.webrtc/builders/iOS64%20Sim%20Debug%20%28iOS%209.0%29/builds/1630/steps/generate%20build%20files%20%28mb%29/logs/stdio

Original issue's description:
> Creating webrtc/modules:module_api
>
> This target keeps track of .h the files under webrtc/modules/include/
> that are not part of any target.
> If a .h file is not part of a target the 'gn check' utility is not
> able to spot if a target is missing a dependency because even if
> it parses '#include' directives it is not able to find a target that
> contains these headers.
>
> BUG=webrtc:7513
> NOTRY=True
>
> Review-Url: https://codereview.webrtc.org/2838873002
> Cr-Commit-Position: refs/heads/master@{#17880}
> Committed: 5a1a092ed0

TBR=kjellander@webrtc.org
# Skipping CQ checks because original CL landed less than 1 days ago.
NOPRESUBMIT=true
NOTREECHECKS=true
NOTRY=true
BUG=webrtc:7513

Review-Url: https://codereview.webrtc.org/2839963005
Cr-Commit-Position: refs/heads/master@{#17881}

webrtc/tools/BUILD.gn

@@ -210,7 +210,6 @@ if (rtc_enable_protobuf) {
       "../call:call_interfaces",
       "../logging:rtc_event_log_impl",
       "../logging:rtc_event_log_parser",
-      "../modules:module_api",
       "../modules/audio_coding:ana_debug_dump_proto",
 
       # TODO(kwiberg): Remove this dependency.
@@ -262,7 +261,6 @@ if (rtc_include_tests) {
     }
 
     deps = [
-      "../modules:module_api",
       "../modules/audio_processing",
       "../system_wrappers:metrics_default",
       "../test:test_support",