[recipes] Define variables in __init__

This may fix weird races in tests.

Bug: skia:
Change-Id: I41c36424c7b559301e915a0892590c74931ae463
Reviewed-on: https://skia-review.googlesource.com/93942
Reviewed-by: Kevin Lubick <kjlubick@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
1 file changed