Unify the value of --ck-ai-balloon-error-background

[oleq]

Provide a description of the task

• We use two different CSS variable names.
• We should have one variable name (a generic one) and update in Figma if needed.

Note:

1. We could have two variable “semantic” names, e.g
   1. --ck-ai-form-error-background
   2. --ck-color-comment-remove-background
2. But then, we may have one specified color for the system like --ck-light-red
3. Then, we can do:
   1. --ck-ai-form-error-background: var(--ck-light-red)
4. This way we have semantic name + unified colors across the application.