Fix replica_promotion-domlevel0 test failures

Integration test is failing due to wrong message being
displayed by ipa. This issue was most probably introduced
by PR:
f51869b
Error messages for domain level 0 and >=1 cases were basically
swapped. This PR is swapping them back.

Reviewed-By: Tibor Dudlak <tdudlak@redhat.com>

ipaserver/install/server/replicainstall.py

@@ -787,8 +787,12 @@ def install_check(installer):
         check_domain_level_is_supported(domain_level)
         if domain_level != constants.DOMAIN_LEVEL_0:
             raise RuntimeError(
-                "You must provide a file generated by ipa-replica-prepare to "
-                "create a replica when the domain is at level 0."
+                "You used the wrong mechanism to install a replica in "
+                "domain level {dl}:\n"
+                "\tFor domain level >= 1 replica installation, first join the "
+                "domain by running ipa-client-install, then run "
+                "ipa-replica-install without a replica file."
+                .format(dl=domain_level)
             )
 
         # Check pre-existing host entry
@@ -1128,12 +1132,8 @@ def promote_check(installer):
         check_domain_level_is_supported(domain_level)
         if domain_level < constants.DOMAIN_LEVEL_1:
             raise RuntimeError(
-                "You used the wrong mechanism to install a replica in "
-                "domain level {dl}:\n"
-                "\tFor domain level >= 1 replica installation, first join the "
-                "domain by running ipa-client-install, then run "
-                "ipa-replica-install without a replica file."
-                .format(dl=domain_level)
+                "You must provide a file generated by ipa-replica-prepare to "
+                "create a replica when the domain is at level 0."
             )
 
         # Check authorization