[nobuildbot] Explicitly name all jobs

This makes it clearer which jobs we're running when looking at
gen_tasks.go.  Doesn't actually change any behavior.

BUG=skia:

Change-Id: Ie4fe639552bd673d3a605e03782a68b5e013cf1d
Reviewed-on: https://skia-review.googlesource.com/4990
Reviewed-by: Ravi Mistry <rmistry@google.com>
Commit-Queue: Eric Boren <borenet@google.com>
tree: a082a45e7672eeeb94c5a58084091cc9f07bf685
  1. recipe_modules/
  2. recipes.py
  3. recipes/