cros_workon: leverage sudo_multi
cros_workon: leverage sudo_multi

The common.sh file has a `sudo_multi` helper to collapse multiple sudo
calls into a single one for a minor speed up.  Use it.

BUG=None
TEST=`./cros_workon --board x86-alex start metrics` still works
TEST=`./cros_workon --board x86-alex stop metrics` still works

Change-Id: I4b670a4d4d6f1402a69f1f7129cadc645cc93225
Reviewed-on: https://gerrit.chromium.org/gerrit/18171
Reviewed-by: Chris Wolfe <4f23406e03c8ffaccefe8744212d3543c02e8d87@chromium.org>
Reviewed-by: David James <f231dc574bbeb62604660cbc162d1b8642a0a3af@chromium.org>
Commit-Ready: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>
Tested-by: Mike Frysinger <8f3f75c74bd5184edcfa6534cab3c13a00a2f794@chromium.org>

nicescale/scripts,smilart/scripts,mjg59/scripts,andrejro/coreos--scripts,fivethreeo/scripts,fivethreeo/scripts,gtank/scripts,andrejro/coreos--scripts,vmware/coreos-scripts,vmware/coreos-scripts,nicescale/scripts,bcwaldon/coreos-scripts,glevand/coreos--scripts,coreos/scripts,mjg59/scripts,mischief/scripts,coreos/scripts,glevand/coreos--scripts,endocode/scripts,trnubo/scripts,crawford/scripts,crawford/scripts,marineam/coreos-scripts,endocode/scripts,bcwaldon/coreos-scripts,nicescale/scripts,trnubo/scripts,fivethreeo/scripts,andrejro/coreos--scripts,marineam/coreos-scripts,sigma/coreos-scripts,zhang0137/scripts,bcwaldon/coreos-scripts,zhang0137/scripts,sigma/coreos-scripts,gtank/scripts,BugRoger/scripts,trnubo/scripts,zhang0137/scripts,mischief/scripts,BugRoger/scripts,mischief/scripts,smilart/scripts,sigma/coreos-scripts,smilart/scripts,marineam/coreos-scripts,BugRoger/scripts,gtank/scripts,endocode/scripts,vmware/coreos-scripts,mjg59/scripts,crawford/scripts