Revert "build runner: print to stderr in dumb terminals"

This reverts commit e6f759e1c64668c50d3ff2d02c64a66c871da0ac.

I changed my mind. I don't like the output because it makes it harder to
find the actual errors in CI logs.
ba77959137Andrew Kelley committed on 3/15/2023, 5:48:14 PMparent20b3533
1 file changedLine totals unavailable