update farm tests (#9687)

* letstest: -ubuntu18.04 +centos9stream +debian11

* letstest: username for centos 9 stream is ec2-user

This is mentioned on https://centos.org/download/aws-images/

* ensure mod_ssl is installed

in centos 9 stream, apache has to be restarted after mod_ssl is
installed, or the snakeoil certificates will not be present and
apache won't start.

this also removes nghttp2 being installed as the relevant bug
is long fixed.

letstest/scripts/test_apache2.sh

@@ -15,8 +15,7 @@ elif [ "$OS_TYPE" = "centos" ]
 then
     CONFFILE=/etc/httpd/conf/httpd.conf
     sudo setenforce 0 || true #disable selinux
-    sudo yum -y install httpd
-    sudo yum -y install nghttp2 || echo this is probably ok but see https://bugzilla.redhat.com/show_bug.cgi?id=1358875
+    sudo yum -y install httpd mod_ssl
     sudo service httpd start
     sudo mkdir -p /var/www/$PUBLIC_HOSTNAME/public_html
     sudo chmod -R oug+rwx /var/www

letstest/targets/targets.yaml

@@ -16,24 +16,28 @@ targets:
     type: ubuntu
     virt: hvm
     user: ubuntu
-  - ami: ami-095192256fe1477ad
-    name: ubuntu18.04LTS
-    type: ubuntu
-    virt: hvm
-    user: ubuntu
   #-----------------------------------------------------------------------------
   # Debian
   - ami: ami-01db78123b2b99496
     name: debian10
     type: ubuntu
     virt: hvm
     user: admin
+  - ami: ami-0fec2c2e2017f4e7b
+    name: debian11
+    type: ubuntu
+    virt: hvm
+    user: admin
   #-----------------------------------------------------------------------------
   # CentOS
-  # This AMI was found on
-  # https://web.archive.org/web/20211126215532/https://wiki.centos.org/Cloud/AWS.
+  # These AMI were found on https://wiki.centos.org/Cloud/AWS.
   - ami: ami-00e87074e52e6c9f9
     name: centos7
     type: centos
     virt: hvm
     user: centos
+  - ami: ami-0c0e36522a91d66e1
+    name: centos9stream
+    type: centos
+    virt: hvm
+    user: ec2-user