fix: use local variable for overwriting ssh keys

Signed-off-by: Bart Jaskulski <bjaskulski@protonmail.com>

includes/deploy/demo.yml

 deploy:demo:
   image: gitlab.wpdesk.dev:5050/wpdesk/docker-tests/amazon-svn-deploy:24.09
+  variables:
+    SSH_KEY: $GLOBAL_SSH_KEY
   environment:
     name: $DEPLOY_SERVER
     url: https://$DEPLOY_SERVER
@@ -43,13 +45,13 @@ deploy:demo:
       variables:
         SSH_DSN: wlgmnfabmq@s125.cyber-folks.pl:/home/wlgmnfabmq/domains/demo.octolize.com/public_html/wp-content/plugins
         SSH_PORT: 222
-        GLOBAL_SSH_PRIV_KEY: $DEMO_FS_SSH_KEY_FILE
+        SSH_KEY: $DEMO_FS_SSH_KEY_FILE
     ## stage.demo.octolize.com
     - if: $DEPLOY_SERVER == 'stage.demo.octolize.com'
       variables:
         SSH_DSN: wlgmnfabmq@s125.cyber-folks.pl:/home/wlgmnfabmq/domains/stage.demo.octolize.com/public_html/wp-content/plugins
         SSH_PORT: 222
-        GLOBAL_SSH_PRIV_KEY: $DEMO_FS_SSH_KEY_FILE
+        SSH_KEY: $DEMO_FS_SSH_KEY_FILE
     ## demo.flexibleinvoices.com
     - if: $DEPLOY_SERVER == 'demo.flexibleinvoices.com'
       variables:
@@ -57,8 +59,8 @@ deploy:demo:
         SSH_PORT: 40022
   before_script:
     - eval "$(ssh-agent -s)"
-    - chmod 600 "$GLOBAL_SSH_PRIV_KEY"
-    - ssh-add "$GLOBAL_SSH_PRIV_KEY"
+    - chmod 600 "$SSH_KEY"
+    - ssh-add "$SSH_KEY"
     - echo "$SSH_KNOWN_HOSTS" | tr -d '\r' > ~/.ssh/known_hosts
   script:
     - rsync -rlDe "ssh -p $SSH_PORT" --delete "$CI_PROJECT_DIR/release/$CI_PROJECT_NAME" $SSH_DSN