Revert "Add wrapper to normalize flags."

This reverts commit 642a49d1eb20b8c5744e745de79ddb585e0f7472.

Reason for revert: Speculative revert, may cause infra failures on perf waterfall

Original change's description:
> Add wrapper to normalize flags.
>
> Bug: None
> Change-Id: I9d43602cc66198a29dbc0e7586d948ee76c5ec84
> Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/145204
> Commit-Queue: Mirko Bonadei <mbonadei@webrtc.org>
> Reviewed-by: Oleh Prypin <oprypin@webrtc.org>
> Cr-Commit-Position: refs/heads/master@{#28532}

TBR=mbonadei@webrtc.org,oprypin@webrtc.org

# Not skipping CQ checks because original CL landed > 1 day ago.

No-Try: True
Bug: None
Change-Id: I1a559931b51b2b4614e765978200d47ee37f9186
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/145328
Commit-Queue: Artem Titarenko <artit@webrtc.org>
Reviewed-by: Artem Titarenko <artit@webrtc.org>
Reviewed-by: Mirko Bonadei <mbonadei@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28554}
diff --git a/tools_webrtc/mb/gn_isolate_map.pyl b/tools_webrtc/mb/gn_isolate_map.pyl
index 0b49ca9..43bdc17 100644
--- a/tools_webrtc/mb/gn_isolate_map.pyl
+++ b/tools_webrtc/mb/gn_isolate_map.pyl
@@ -127,10 +127,6 @@
   "webrtc_perf_tests": {
     "label": "//:webrtc_perf_tests",
     "timeout": 3600,  # 1 hour
-    "type": "script",
-    "script": "//tools_webrtc/flags_compatibility.py",
-    "args": [
-      "./webrtc_perf_tests",
-    ],
+    "type": "raw",
   },
 }