Build process: we should not be deleting build directories after a build - they are deleted beforehand anyway, and may contain useful info

[dyaandys]

At 0978c51

In Jenkinsfile we have
rm -rf _ ship
build_ride
stash ship
rm -rf _ ship

That last rm -rf is both unnecessary, and also unhelpful - if the builds thinks it's been successful but hasn't all the files will have been deleted which is unhelpful ! So let's delete that second rm -rf.

[dyaandys]

As a minor aside, the stage should be called "Notarise" .. I'll make the change to see if the build is successful .. and then change one rm at a time.