Remove the special-case check on kf5umbrella by supporting all
virtual/misspelled dependencies in dependency-data without raising fatal
errors. --verbose still warns about missing dependencies (even with
kf5umbrella) and the worst case is that we try to build modules out of
order until someone notices the metadata is wrong.

That's a much better worst case than that of a couple of days ago
("kdesrc-build won't even start").

BUG:344814