remove debian 8 and 9 corpses,

originally it was deprecated in this commit:
07a09bd

Author: SimonHoenscheid

manifests/globals.pp

@@ -194,8 +194,6 @@
     },
     'Debian' => $facts['os']['name'] ? {
       'Debian' => $facts['os']['release']['major'] ? {
-        '8'     => '9.4',
-        '9'     => '9.6',
         '10'    => '11',
         '11'    => '13',
         default => undef,

spec/defines/server/default_privileges_spec.rb

@@ -113,7 +113,7 @@
     end
 
     context 'schemas on postgres < 10.0' do
-      include_examples 'Debian 9'
+      include_examples 'RedHat 7'
 
       let :params do
         {

spec/spec_helper_local.rb

@@ -122,10 +122,6 @@ def param(type, title, param)
   end
 end
 
-shared_context 'Debian 9' do
-  let(:facts) { on_supported_os['debian-9-x86_64'] }
-end
-
 shared_context 'Debian 10' do
   let(:facts) { on_supported_os['debian-10-x86_64'] }
 end