After we switch to swarming builds, many builders will frequently be reused for different boards/branches as the 'normal' case.

In addition, we have options to allow swarming to prefer builders with hot caches, if the caches are moved out of the build root into special cache directories identified by directory name.

This will change our performance around how we cache various build related behaviors enough to rethink that caching.

We need to investigate how to best take advantage of this and adjust the recipe to match.