community-build: turn off SNAPSHOT updating in the meta-build too
community-build: turn off SNAPSHOT updating in the meta-build too

We already start sbt with this command, but that only takes effect in
the build, not the meta-build (and this still doesn't cover the
meta-meta-...-builds, oh well).

sjrd/dotty,dotty-staging/dotty,dotty-staging/dotty,dotty-staging/dotty,sjrd/dotty,sjrd/dotty,lampepfl/dotty,lampepfl/dotty,dotty-staging/dotty,lampepfl/dotty,lampepfl/dotty,lampepfl/dotty,sjrd/dotty,dotty-staging/dotty,som-snytt/dotty,som-snytt/dotty,som-snytt/dotty,sjrd/dotty,som-snytt/dotty,som-snytt/dotty