[test] Fix typo in test config

TBR=yangguo@chromium.org
NOTRY=true

Bug: v8:7302
Change-Id: Ica0f28fc8ce8184ffe8f51d940a77710e98b5d5a
Reviewed-on: https://chromium-review.googlesource.com/867039Reviewed-by: Michael Achenbach <machenbach@chromium.org>
Commit-Queue: Michael Achenbach <machenbach@chromium.org>
Cr-Commit-Position: refs/heads/master@{#50598}

infra/testing/client.v8.pyl

@@ -11,7 +11,7 @@
   #   {'name': 'benchmarks', 'variant': 'default', 'shards': 1},
   # ],
 
-  'V8 Linux - debug ': [
+  'V8 Linux - debug': [
     {'name': 'd8testing', 'variant': 'code_serializer', 'shards': 1},
     {'name': 'mozilla', 'variant': 'code_serializer', 'shards': 1},
     {'name': 'test262_variants', 'variant': 'code_serializer', 'shards': 1},