runtime(sbt): do not set b:did_ftplugin before sourcing scala ftplugin(vim/vim#13657)
The `b:did_ftplugin` guard was set and prevented us from actually sourcing `ftplugin/scala.vim`. Since the latter script also sets the guard properly, we can simply remove the guard here.
5a68cdf149
Co-authored-by: Karl Yngve Lervåg <karl.yngve@lervag.net>
