reduce CI bill and improve build speed

[garypen]

The long pole on our build is the arm build/test step. Also, running everything in parallel is expensive.

Let's address both of those problems:

• require lint to succeed before starting build/test jobs
• give more resources to arm jobs to allow them to complete faster
• tweak the build setting for both arm and amd to use resources more effectively

Result:

• total build time is reduced by ~15% in my test runs (even with waiting for lint first)
• billing should be reduced by less renovate waste-fullness when lint fails

[github-actions]

@garypen, please add a /NEXT_CHANGELOG.md entry for this PR to the appropriate section!