Do not build 'all' on iOS bots (part 2).

This is a follow-up CL to stop building 'all' on iOS bots since they
will end up building invalid Abseil build targets.

Original CL: https://webrtc-review.googlesource.com/70140.

Bug: webrtc:8821
Change-Id: I58e4dbc10377f670ce80552a9b695607b81da284
Reviewed-on: https://webrtc-review.googlesource.com/71280
Reviewed-by: Patrik Höglund <phoglund@webrtc.org>
Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#22960}

tools_webrtc/ios/internal.client.webrtc/iOS64_Debug.json

@@ -15,7 +15,7 @@
     "MAC_TOOLCHAIN_REVISION": "8E2002-1"
   },
   "use_analyze": false,
-  "additional_compile_targets": [ "all" ],
+  "additional_compile_targets": [],
   "configuration": "Debug",
   "bucket": "chromium-webrtc",
   "tests": [

tools_webrtc/ios/internal.client.webrtc/iOS64_Perf.json

@@ -15,7 +15,7 @@
     "MAC_TOOLCHAIN_REVISION": "8E2002-1"
   },
   "use_analyze": false,
-  "additional_compile_targets": [ "all" ],
+  "additional_compile_targets": [],
   "configuration": "Release",
   "bucket": "chromium-webrtc",
   "tests": [

tools_webrtc/ios/internal.client.webrtc/iOS64_Release.json

@@ -16,7 +16,7 @@
     "MAC_TOOLCHAIN_REVISION": "8E2002-1"
   },
   "use_analyze": false,
-  "additional_compile_targets": [ "all" ],
+  "additional_compile_targets": [],
   "configuration": "Release",
   "bucket": "chromium-webrtc",
   "tests": [