remove useless grep in quiet refresh

In commit da77c23, getuto "made quiet
mode more quiet". It did this by piping the output of some gpg calls to
a grep pipe, that filtered out any "expected warnings" in the form of no
user IDs emitted by keys.openpgp.org, while mostly leaning on gpg
--quiet to be quiet.

In commit 15fcac9, getuto added -q to
grep, with the note "Also, use grep -q to honour --quiet". This meant
that grep was instructed to emit zero output if at all possible, and is
intended to use for scripts that want to check the return code of grep
to see whether matches were found. (getuto does NOT check this.)

Given this is incorrect use of grep, we instead just redirect all stdout
and stderr to /dev/null. It is semantically identical to what we already
do, but with one less fork+exec and the intent is far clearer.

Author: eli-schwartz

getuto

@@ -83,10 +83,6 @@ getuto_refresh() {
 	else
 		[[ -n ${QUIET} ]] || einfo "gnupg keyring for package signatures already up-to-date."
 	fi
-
-	# If we got here, everything is fine. Empty a silly string to keep the grep happy
-	# on the output of getuto_refresh.
-	[[ -n ${QUIET} ]] && echo OK || true
 }
 
 
@@ -196,7 +192,7 @@ else
 	export LC_ALL=C.UTF8
 
 	if [[ -n ${QUIET} ]] ; then
-		getuto_refresh |& grep -qv ": no user ID"
+		getuto_refresh >/dev/null 2>&1
 	else
 		getuto_refresh
 	fi