fix: prepare script respects scriptshell config

[milaninfy]

Prepare script respects scriptshell config if passed matching behaviour of npm run <script>

fixes: npm/cli#7723

[wraithgar]

This was intentional. It is how, for example, git repos work. The purpose of the prepare lifecycle script is to prepare local directories to work, so this flag was not added here. This flag currently does not differentiate between scripts in your package itself, and those of the packages your are installing, so there is no way for folks to ignore their package's scripts while still being able to install git refs. This is the compromise.