Remove append-bottom-2 CSS rule

What does this MR do?

Removes the append-botom-2 CSS class, no replacements were needed as no other files used this class

Issue #217418

Screenshots

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• [-] Database guides
• [-] Separation of EE specific content