Build task should clear node binaries by default

[epixa]

The default behavior of the build task should be to start with a clean slate, but the current behavior in regard to node binaries is to reuse any existing binaries that have already been downloaded. Binary reuse should be possible via an opt-in CLI argument, but they should be redownloaded if the argument is absent.

This is all a part of the larger theme that people shouldn't need to manually clean up their build environment each time to create consistent and reliable builds, which requires a human to be involved for all actual releases. The unified release process will be completely automated though, so it's imperative that it works consistently and automatically.

[ppisljar]

i updated #7746 to reflect this behaviour