(SIMP-10204) Ensure testing with CentOS 8.4 (#57)

- update the EL8 nodes in the acceptance tests
  to run with generic/centos8 to make sure they using
  CentOS 8.4
- udate oracle 7 node to generic from onyxpoint.

SIMP-10204 #comment acpid updates
SIMP-10206 #close

spec/acceptance/nodesets/default.yml

@@ -15,7 +15,7 @@ HOSTS:
 
   el8:
     platform: el-8-x86_64
-    box: centos/8
+    box: generic/centos8
     hypervisor: <%= hypervisor %>
 
 CONFIG:

spec/acceptance/nodesets/oel.yml

@@ -10,7 +10,7 @@ HOSTS:
     roles:
       - default
     platform: el-7-x86_64
-    box: onyxpoint/oel-7-x86_64
+    box: generic/oracle7
     hypervisor: <%= hypervisor %>
 
   oel8: