cross-busybox.xml: added 1.22.1, updated config file path for ARM
cross-preflight.xml: prefix test binary with architecture

- Keep only the past 10 builds, not 10 days worth of builds
cross-preflight-cron.xml: added API launcher for cross-preflight

- Launches 2 jobs, one for each BUILD_ARCH in `cron-preflight`
cross-busybox-cron.xml: added API launcher for cross-busybox

- Launches 2 jobs, one for each BUILD_ARCH in `cron-busybox`