tests: better grep of lxd.pot
tests: better grep of lxd.pot

In particular, multiline strings only have "msgid" on the first line, so
any change in a multiline string not on the first line wasn't detected by
the previous grep.

Signed-off-by: Tycho Andersen <10c18fcb898ee6b17d6575d444b125d10b3f4d6a@canonical.com>

stgraber/lxd,hallyn/lxd,stgraber/lxd,techtonik/lxd,hallyn/lxd,Skarlso/lxd,hallyn/lxd,akshaykarle/lxd,akshaykarle/lxd,techtonik/lxd,Skarlso/lxd,Skarlso/lxd,ollie314/lxd,yura-pakhuchiy/lxd,atxwebs/lxd,atxwebs/lxd,erikmack/lxd,mjeanson/lxd,jsavikko/lxd,georghopp/lxd,lxc/lxd,hallyn/lxd,jsavikko/lxd,stgraber/lxd,hallyn/lxd,chrisglass/lxd,atxwebs/lxd,atxwebs/lxd,stgraber/lxd,akshaykarle/lxd,georghopp/lxd,erikmack/lxd,pcdummy/lxd,stgraber/lxd,lxc/lxd,chrisglass/lxd,dustinkirkland/lxd,pcdummy/lxd,ollie314/lxd,stgraber/lxd,mjeanson/lxd,dustinkirkland/lxd,lxc/lxd,jsavikko/lxd,yura-pakhuchiy/lxd,lxc/lxd,Skarlso/lxd,dustinkirkland/lxd,stgraber/lxd,hallyn/lxd,techtonik/lxd,lxc/lxd,georghopp/lxd,pcdummy/lxd,yura-pakhuchiy/lxd,ollie314/lxd,mjeanson/lxd,chrisglass/lxd,lxc/lxd,lxc/lxd,erikmack/lxd