[BUGFIX] RTE Remove Format removes too much

The remove format function with msword selected removes too much
content when there is more than one style block in content.

Note: Thanks to Volker Burggräf

Resolves: #58310
Releases: 6.2, 6.1, 4.5
Change-Id: Ia29767239d92fde20ceee97ece47786d3fd3a9a5
Reviewed-on: https://review.typo3.org/30223
Reviewed-by: Stanislas Rolland
Tested-by: Stanislas Rolland