Remove Bootstrap 4's Cards class name from Epics

What does this MR do?

Removes Bootstrap 4's Cards class name from Epics.

cf. CE-only MR: !48004 (merged)

Screenshots (strongly suggested)

No regression confirmed:

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Style guides
• Separation of EE specific content

Closes #289967 (closed)