[test] Fix predictable builder after swarming switch

NOTRY=true
TBR=sergiyb@chromium.org

Bug: chromium:830557
Change-Id: Ie9022b04cb5858654c6903f38031c860e8681b9e
Reviewed-on: https://chromium-review.googlesource.com/c/1296478Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#56899}

tools/BUILD.gn

@@ -50,6 +50,7 @@ group("v8_testrunner") {
   data = [
     # Also add the num-fuzzer wrapper script in order to be able to run the
     # num-fuzzer on all existing isolated V8 test suites.
+    "predictable_wrapper.py",
     "run-num-fuzzer.py",
     "run-tests.py",
     "testrunner/",