runner: try to run without --legacy-peer-deps
This is aimed to resolve errors like 'Missing: acorn@8.11.3 from lock file' and Cannot find module 'stylelint'.
In the cases I tried locally npm worked fine without --legacy-peer-deps. Let's give that a try, if this starts producing new errors we haven't seen before we can add a step to try without first and if it fails retry with --legacy-peer-deps and run npm install afterwards to re-generate the lock file.
Bug: T356567
Bug: T356595