Revert "Github Actions: use MD5 pass encryption to support PostgreSQL 14 (#3691)"

This workaround is not needed anymore, thanks to p1_pgsql 3bf645b,
included in p1_pgsql 1.1.13, and used in ejabberd 21.12.
This reverts commit 964cb3aaca.

.github/workflows/ci.yml

@@ -52,8 +52,6 @@ jobs:
 
     - name: Prepare databases
       run: |
-        sudo sed -i 's|#password_encryption.*|password_encryption = md5|g' /etc/postgresql/14/main/postgresql.conf
-        sudo sed -i 's|scram-sha-256|md5|g' /etc/postgresql/14/main/pg_hba.conf
         sudo systemctl start mysql.service
         sudo systemctl start postgresql.service
         mysql -u root -proot -e "CREATE USER 'ejabberd_test'@'localhost'