Remove prefixes from transition CSS property

What does this MR do?

Removes vendor prefixes from the CSS transition property

Are there points in the code the reviewer needs to double check?

None

Why was this MR needed?

Reduces unnecessary CSS

Screenshots (if relevant)

None

Does this MR meet the acceptance criteria?

• CHANGELOG entry added
• Tests
  • All builds are passing
• Conform by the style guides
• Branch has no merge conflicts with master (if you do - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes #21614 (closed)

Restored source branch remove-transition-prefix

Added 29 commits:

• edadb018...43ddf0ca - 28 commits from branch gitlab-org:master
• 5d471961 - Remove prefixes from transition CSS property

@smcgivern can you review and assign please?

@annabeldunstone is this one you can help with?

Added ~164274 frontend labels

Reassigned to @annabeldunstone

Added 35 commits:

• 5d471961...4de9e727 - 34 commits from branch gitlab-org:master
• 5c2489e4 - Remove prefixes from transition CSS property

Reassigned to @ClemMakesApps

Added 1 commit:

• 7b09a27e - Remove prefixes from transition CSS property

Resolved all discussions

Reassigned to @annabeldunstone

Looks good in IE11

Status changed to merged

mentioned in commit 2c3586d2

Resolved all discussions