chimney script: add a prompt before deleting the previous blobber

currently, when a user runs chimney script, and if there any previous blobber its data will be erased without warning.

We if there is a previous blobber deployment, we should prompt the user and show a warning telling:
"A blobber already exists on this server. Do you wish to delete blobber currently deployed on this server [N/y]:"

Find the chimney script in the repository, likely a shell script that handles blobber deployment. Look for the section where it checks for an existing blobber and deletes it. Add a prompt using 'read' to ask for user confirmation before deletion. Test the script locally to ensure the warning appears and the deletion proceeds only on 'y' or 'Y'.

Written by the indexing model from the issue text.