fix(databasus): mariadb-dump path error & missing ui/build dir on update

- Install mariadb-client and create symlinks at paths expected by
  Databasus (/usr/local/mariadb-{10.6,12.1}/bin/mariadb-dump and
  /usr/local/mysql-{5.7,8.0,8.4,9}/bin/mysqldump)
- Add mkdir -p /opt/databasus/ui/build before cp in update script

Closes #12255

ct/databasus.sh

@@ -49,6 +49,7 @@ function update_script() {
     $STD /root/go/bin/swag init -g cmd/main.go -o swagger
     $STD env CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o databasus ./cmd/main.go
     mv /opt/databasus/backend/databasus /opt/databasus/databasus
+    mkdir -p /opt/databasus/ui/build
     cp -r /opt/databasus/frontend/dist/* /opt/databasus/ui/build/
     cp -r /opt/databasus/backend/migrations /opt/databasus/
     chown -R postgres:postgres /opt/databasus