source_tree_test_config: restructure config for better readability

I lay out the intention here: https://crbug.com/1130018#c19

This structure makes it a lot clearer how the rules take effect and
combine. Roughly speaking,
1. Take default set of CQ test suites
2. Apply subtractive rules to remove some suites
3. Apply additive rules to add additional suites
4. Combine rule results for files in different source test configs

After this, I'll dual write to infra/config, then update infra/go to use
the new fields, then remove dual writing, then remove the old proto
messages/fields.

Bug: 1130018
Change-Id: I104b751912001368783bcfbce82816949322b4e3
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/infra/proto/+/2436933
Commit-Queue: Sean Abraham <seanabraham@chromium.org>
Reviewed-by: Dhanya Ganesh <dhanyaganesh@chromium.org>
Reviewed-by: Prathmesh Prabhu <pprabhu@google.com>
2 files changed