Disable use_fuzztest_wrapper for bots not using libfuzzer.

This is to avoid a dependency on Chromium //base on bots that don't need it:
1bd0da6657:libfuzzer/BUILD.gn;l=164

Bug: None
Change-Id: Idf3ef2a313641abcd3741e0ef7b2fac61c629068
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/367640
Commit-Queue: Jeremy Leconte <jleconte@webrtc.org>
Reviewed-by: Björn Terelius <terelius@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#43360}

.gn

@@ -81,4 +81,7 @@ default_args = {
   # WebRTC doesn't use jni_zero's multiplexing. Since this causes an error
   # let's temporarily disable it.
   enable_jni_multiplexing = false
+
+  # This adds a dependency to //base.
+  use_fuzztest_wrapper = false
 }

tools_webrtc/mb/mb_config.pyl

@@ -484,7 +484,8 @@
       'gn_args': 'ios_code_signing_identity_description="Apple Development"',
     },
     'libfuzzer': {
-      'gn_args': 'use_libfuzzer=true',
+      # use_fuzztest_wrapper adds a dependency to //base.
+      'gn_args': 'use_libfuzzer=true use_fuzztest_wrapper=true',
     },
     'lsan': {
       'gn_args': 'is_lsan=true',