[BUGFIX] sys_news on login with twice hsc

Set RteHtmlParser in dontHSC_rte modus to fix garbled output.

Resolves: #25188
Releases: 6.2, 6.1
Change-Id: Ib01c3f6dcf1729b1979003c207aa622cc5c9b5c3
Reviewed-on: https://review.typo3.org/30690
Reviewed-by: Xavier Perseguers
Tested-by: Xavier Perseguers