(cherry picked from commit bc5d484)

(cherry picked from commit 5d8504b)

(cherry picked from commit f459ca5)

For remote stores the log messages are already forwarded as structured
STDERR_RESULT messages so the old format is duplicate information.  But
still included with -vvv since it could be useful for debugging
problems.

    $ nix build -L /nix/store/nl71b2niws857ffiaggyrkjwgx9jjzc0-foo.drv --store ssh-ng://localhost
    Hello World!
    foo> Hello World!
    [1/0/1 built] building foo

Fixes #3556

The raw stderr output isn't logged anymore so the build logs need to be
printed by the default logger in order for the old commands like
nix-build to still show build output.

remote-store: don't log raw stderr by default