Let formatlesspaste plugin remove empty tags RT#57942

Previously, it would try to unwrap() an empty jQuery object to
remove an empty element, now it just removes an element if it's
empty.

(cherry picked from commit b0fa832b73c6d75c9836f6dbee6610f0bb968c5b)
Merge branch 'hotfix-0.24.x' of github.com:alohaeditor/Aloha-Editor into hotfix