Revert "reclient_helper: tuning local execution parameter"

This reverts commit 791894e4c4.

Reason for revert: This makes the performance of Siso+Reclient builds
unstable by trigging too many racing local.

Original change's description:
> reclient_helper: tuning local execution parameter
>
> With this CL, build time of chrome with non-cache hit case improved a
> bit on P620 Linux workstation.
>
> ```
> Benchmark 1: RBE_local_resource_fraction=0.4 RBE_racing_bias=0.7 RBE_remote_accept_cache=false autoninja -C out/Default chrome
>   Time (mean ± σ):     337.697 s ± 11.439 s    [User: 3086.301 s, System: 1362.952 s]
>   Range (min … max):   327.732 s … 351.680 s    5 runs
> ```
>
> ```
> Benchmark 1: RBE_remote_accept_cache=false autoninja -C out/Default chrome
>   Time (mean ± σ):     347.795 s ± 15.906 s    [User: 2764.181 s, System: 1199.244 s]
>   Range (min … max):   331.964 s … 367.898 s    5 runs
> ```
>
> Bug: 352463976
> Change-Id: Ic9732583857ce175888a7ec65cf9e323529f0a07
> Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/5693250
> Commit-Queue: Takuto Ikuta <tikuta@chromium.org>
> Reviewed-by: Junji Watanabe <jwata@google.com>
> Auto-Submit: Takuto Ikuta <tikuta@chromium.org>

Bug: 352463976, 379999879
Change-Id: Ibd2b6c7a7e17dc5050df8bb20f4e2743b97a8d6d
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/tools/depot_tools/+/6034205
Reviewed-by: Philipp Wollermann <philwo@google.com>
Reviewed-by: Takuto Ikuta <tikuta@chromium.org>
Commit-Queue: Junji Watanabe <jwata@google.com>
Reviewed-by: Fumitoshi Ukai <ukai@google.com>

reclient_helper.py

@@ -264,13 +264,8 @@ def set_reproxy_path_flags(out_dir, make_dirs=True):
 
 
 def set_racing_defaults():
-    if sys.platform == 'linux':
-        os.environ.setdefault("RBE_local_resource_fraction", "0.4")
-        os.environ.setdefault("RBE_racing_bias", "0.7")
-    else:
-        # TODO(b/352463976): tune this on non-Linux platform too.
-        os.environ.setdefault("RBE_local_resource_fraction", "0.2")
-        os.environ.setdefault("RBE_racing_bias", "0.95")
+    os.environ.setdefault("RBE_local_resource_fraction", "0.2")
+    os.environ.setdefault("RBE_racing_bias", "0.95")
 
 
 def set_mac_defaults():