(PUP-3157) Allow variable DNS name order in helpful error cert name test

This commit updates the
`helpful_error_message_when_hostname_not_match_server_certificate.rb`
test to allow for the order in which the DNS names are enumerated back
from the master server's certificate to be variable.  This allows the
test to not errantly fail depending upon the order in which the names
were actually signed into the certificate.
Merge pull request #3034 from camlow325/maint/master/PUP-3157-helpful-error-message-dns-name-order

(PUP-3157) Allow variable DNS name order in helpful error cert name test