Resolve "Review parallel count for `rspec *` jobs"

.gitlab/ci/rails.gitlab-ci.yml

@@ -102,13 +102,13 @@ rspec migration pg9:
   extends:
     - .rspec-base-pg9
     - .rspec-base-migration
-  parallel: 4
+  parallel: 5
 
 rspec migration pg9-foss:
   extends:
     - .rspec-base-pg9-foss
     - .rspec-base-migration
-  parallel: 4
+  parallel: 5
 
 rspec unit pg9:
   extends: .rspec-base-pg9
@@ -120,11 +120,11 @@ rspec unit pg9-foss:
 
 rspec integration pg9:
   extends: .rspec-base-pg9
-  parallel: 6
+  parallel: 8
 
 rspec integration pg9-foss:
   extends: .rspec-base-pg9-foss
-  parallel: 6
+  parallel: 8
 
 rspec system pg9:
   extends: .rspec-base-pg9
@@ -140,7 +140,7 @@ rspec unit pg10:
 
 rspec integration pg10:
   extends: .rspec-base-pg10
-  parallel: 6
+  parallel: 8
 
 rspec system pg10:
   extends: .rspec-base-pg10
@@ -170,11 +170,11 @@ rspec-ee unit pg9:
 
 rspec-ee integration pg9:
   extends: .rspec-ee-base-pg9
-  parallel: 3
+  parallel: 4
 
 rspec-ee system pg9:
   extends: .rspec-ee-base-pg9
-  parallel: 5
+  parallel: 6
 
 rspec-ee migration pg10:
   extends: