Bug 1473276 'which' is non-standard, use 'command -v' in partials r=mtabara

This will start to cause an error when a newer shellcheck is available in CI

Differential Revision: https://phabricator.services.mozilla.com/D1940

--HG--
extra : moz-landing-system : lando

taskcluster/docker/funsize-update-generator/scripts/mbsdiff_hook.sh

@@ -20,7 +20,7 @@ CACHE_THRESHOLD=500000
 NAMESPACE='releng.releases.partials'
 if [ -e "${HOME}/.dogrc" ]
 then
-    METRIC_CMD="$(which dog)"
+    METRIC_CMD="$(command -v dog)"
 else
     METRIC_CMD="echo"
 fi