Revert "Use Swiftshader by default when fuzzing"

This reverts commit d08a14b70982a90423f4965ae5625847316de09e.

Reason for revert: This breaks the Mac fuzzer builds because it tries
to build with Swiftshader without Vulkan enabled. Reverting this now
to unblock the roll while I work on a fix.

Original change's description:
> Use Swiftshader by default when fuzzing
> 
> Note: This still requires Chromium to have set dawn_swiftshader_dir
> to take effect.
> 
> Bug: dawn:295
> Change-Id: I0c953196630dd2694f68d290e6f3f1e427c20a2f
> Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/14821
> Reviewed-by: Corentin Wallez <cwallez@chromium.org>
> Reviewed-by: Kai Ninomiya <kainino@chromium.org>
> Commit-Queue: Austin Eng <enga@chromium.org>

TBR=cwallez@chromium.org,kainino@chromium.org,enga@chromium.org

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

Bug: dawn:295
Change-Id: I7b73d5edc844e090d5d2c8efe9efacc60040463e
Reviewed-on: https://dawn-review.googlesource.com/c/dawn/+/14940
Reviewed-by: Austin Eng <enga@chromium.org>
Reviewed-by: Corentin Wallez <cwallez@chromium.org>
Commit-Queue: Austin Eng <enga@chromium.org>
diff --git a/scripts/dawn_features.gni b/scripts/dawn_features.gni
index f2e9586..7cbb82f 100644
--- a/scripts/dawn_features.gni
+++ b/scripts/dawn_features.gni
@@ -56,8 +56,7 @@
   # dawn_swiftshader_dir variable in build_overrides/dawn.gni
   # Because of how the Vulkan loader works, setting this make Dawn only able
   # to find the Swiftshader ICD and not the others.
-  # Enabled by default when fuzzing.
-  dawn_use_swiftshader = build_with_chromium && use_fuzzing_engine
+  dawn_use_swiftshader = false
 
   # Enables error injection for faking failures to native API calls
   dawn_enable_error_injection =