Remove legacy accounts and passwords.
### What problem does this PR solve?
Remove leftover account and password in
agent/templates/sql_assistant.json
### Type of change
- [x] Other (please describe):
### What does this PR solve?
German translation for all agent template and optimizing line breaks in
the title for the new translation.
### Type of change
- [x] New Feature (non-breaking change which adds functionality)
### What problem does this PR solve?
Updated SQL assistant template to wrap variables like 'sys.query' and
'Agent:WickedGoatsDivide@content' in curly braces for better template
variable syntax consistency.
### Type of change
- [x] Bug Fix (non-breaking change which fixes an issue)