Remove MESHRR_MODE environment variable

[jrokeach]

meshrr/meshrr/run.sh

Lines 46 to 53 in 9620996

	if [[ "$MESHRR_MODE" == 'evpnrs' ]] || [[ "$MESHRR_MODE" == 'routeserver' ]] ; then
	template='juniper-evpnrs.conf.j2'
	elif [[ "$MESHRR_MODE" == 'ipv4rr' ]] || [[ "$MESHRR_MODE" == 'routereflector' ]] || [[ -z $MESHRR_MODE ]]; then
	template='juniper-ipv4rr.conf.j2'
	else
	echo "Invalid MESHRR_MODE set. Must be empty or one of [ 'evpnrs' 'ipv4rr' ]."
	exit 1
	fi

Adds complexity with little benefit. Move to only one default template and override the template for the evpnrs use case.