Add perf-flutter namespace so it gets backed up.
Add perf-flutter namespace so it gets backed up.

Bug: skia:9789
Change-Id: I22238cd6fd0e70e011081fabfc7797aa8086e207
Reviewed-on: https://skia-review.googlesource.com/c/buildbot/+/266936
Reviewed-by: Ravi Mistry <9fa2e7438b8cb730f96b74865492597170561628@google.com>
Commit-Queue: Joe Gregorio <b9cf2471ff6d33504cafe8e6f356b732b2cadced@google.com>

google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot,google/skia-buildbot