Sync only the current branch and use a shallow checkout

Tried this out locally and it shrunk the size of the checkout from 1010M
to 586M and shaved a few seconds off the running time as well.

NoTry: true
Bug: skia:7016
Change-Id: I472712e88d2cf30f0cfd71a373630d12a4937684
Reviewed-on: https://skia-review.googlesource.com/44820
Reviewed-by: Mike Klein <mtklein@google.com>
Commit-Queue: Ravi Mistry <rmistry@google.com>
1 file changed