Architecture config not loaded into subrepo's for plugins when crosscompiling

[Tatskaari]

Plugin config for the target architecture in the platform config files (e.g. .plzconfig_darwin_amd64) is not respected

[stale[bot]]

This issue has been automatically marked as stale because it has not had any recent activity in the past 90 days. It will be closed if no further activity occurs. If you require additional support, please reply to this message. Thank you for your contributions.

[samwestmoreland]

Here's a test that reproduces this issue: https://github.com/thought-machine/please/pull/2876