revert(fleet): switch back to MySQL, MariaDB incompatible with Fleet migrations

MariaDB fails on migration 20240905200000_UninstallPackages due to
SQL syntax incompatibility (MODIFY COLUMN ... NULL). Use real MySQL
with manual DB setup instead of setup_mariadb_db.

install/fleet-install.sh

@@ -13,8 +13,17 @@ setting_up_container
 network_check
 update_os
 
-setup_mariadb
-MARIADB_DB_NAME="fleet" MARIADB_DB_USER="fleet" setup_mariadb_db
+setup_mysql
+
+msg_info "Setting up Database"
+FLEET_DB_PASS=$(openssl rand -base64 18 | tr -dc 'a-zA-Z0-9' | head -c 13)
+$STD mysql -u root <<EOSQL
+CREATE DATABASE fleet;
+CREATE USER 'fleet'@'localhost' IDENTIFIED BY '${FLEET_DB_PASS}';
+GRANT ALL PRIVILEGES ON fleet.* TO 'fleet'@'localhost';
+FLUSH PRIVILEGES;
+EOSQL
+msg_ok "Set up Database"
 
 fetch_and_deploy_gh_release "fleet" "fleetdm/fleet" "prebuild" "latest" "/opt/fleet" "fleet_v*_linux.tar.gz"
 
@@ -25,7 +34,7 @@ cat <<EOF >/opt/fleet/.env
 FLEET_MYSQL_ADDRESS=127.0.0.1:3306
 FLEET_MYSQL_DATABASE=fleet
 FLEET_MYSQL_USERNAME=fleet
-FLEET_MYSQL_PASSWORD=${MARIADB_DB_PASS}
+FLEET_MYSQL_PASSWORD=${FLEET_DB_PASS}
 FLEET_SERVER_ADDRESS=0.0.0.0:8080
 FLEET_SERVER_TLS=false
 FLEET_AUTH_JWT_KEY=${JWT_KEY}
@@ -42,8 +51,8 @@ msg_info "Creating Service"
 cat <<EOF >/etc/systemd/system/fleet.service
 [Unit]
 Description=Fleet
-After=network.target mariadb.service
-Requires=mariadb.service
+After=network.target mysql.service
+Requires=mysql.service
 
 [Service]
 Type=simple