[test] Add missing mozilla test suite to win trybots

TBR=sergiyb@chromium.org

Bug: v8:8790
Change-Id: Iceb77dfa511eebd2802efb5bd4c94fc67131b67e
Reviewed-on: https://chromium-review.googlesource.com/c/1454611Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Reviewed-by: Sergiy Belozorov <sergiyb@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#59390}

infra/testing/builders.pyl

@@ -424,6 +424,7 @@
       'os': 'Windows-7-SP1',
     },
     'tests': [
+      {'name': 'mozilla'},
       {'name': 'test262'},
       {'name': 'v8testing', 'shards': 2},
     ],
@@ -467,6 +468,7 @@
       'os': 'Windows-7-SP1',
     },
     'tests': [
+      {'name': 'mozilla'},
       {'name': 'test262'},
       {'name': 'v8testing', 'shards': 2},
       {'name': 'v8testing', 'variant': 'extra'},