Revert "Allow changing the PHP version for CI tests"

This reverts commit dd773fd.

Author: vmcj

.github/jobs/ci_settings.sh

@@ -34,15 +34,6 @@ mysql_user () {
     echo "$1" | mysql -udomjudge -pdomjudge ${2:-} | tee -a "$ARTIFACTS"/mysql.txt
 }
 
-show_phpinfo() {
-    phpversion=$1
-    section_start "Show the new PHP info"
-    update-alternatives --set php /usr/bin/php"${phpversion}"
-    php -v
-    php -m
-    section_end
-}
-
 section_start () {
     if [ "$#" -ne 1 ]; then
         echo "Only 1 argument is needed for GHA, 2 was needed for GitLab."