1. 51-update-bash.bashrc:
- Add comment to '/etc/bashrc' ('The following code is added by XYZ
script').
- Removal of OPTS_FILE variable.

2. replace-su-with-sudo.sh:
- Updated comment to better describe the role of this script.
- Moved output stuff to '/usr/local/bin/replace-su-with-sudo'.
- Moved translation stuff to '/usr/local/bin/replace-su-with-sudo'.
- 'su' function will now simply call the 'replace-su-with-sudo' script.

3. replace-su-with-sudo:
- Created new script
- It handles the logic and output (with translation) of 'Please use sudo
instead' message.

4. tails_is_password_set.py
- Moved from /usr/local/bin/ to /usr/local/lib/python3/dist-packages/
- Removed main() function. This file is now just a library; not meant to
be executed as a standalone script.

5. 'POTFILES.in' and 'refresh-translations':
- Modified to accommodate the changes made in 'replace-su-with-sudo.sh'
and 'replace-su-with-sudo'.