fix: Credit Limit Email not working

[marination]

Issues:

• get_users_with_role on line 396 returns a list of users. Same list was cast into yet another list on line 429. Thus recipients = [["abc@example.com"]]. This caused :

       File ".../apps/frappe/frappe/email/queue.py", line 85, in send
           recipients = list(set(recipients))
       TypeError: unhashable type: 'list'
  

• The credit controllers users list was formatted to ===> user (Fullname). This overwrote recipients list from ["abc@example.com"] to ["John Doe (abc@example.com)] which is invalid as a recipient address.
  
  

Fixes:

• don't cast into list again while invoking frappe.sendmail
• Separate credit controller users list and the formatted list with better naming to reduce confusion. Send credit controller users list as argument in frappe.sendmail

[deepeshgarg007]

@marination One more PR for the fix is also open #23026