[Backport 12.2] Regression: Authors get to see the 'Add channel' in channel mngr even if they are not webmaster

Note : Not sure yet if this is a channelmngr or hst issue. For now created the issue in channel mgr.

cms version

<version>11.2.7-SNAPSHOT</version>

works as expected.

version 12 seems broken.

Note that apart from that the 'Add channel' is shown, an author cannot actually create a new channel because when trying so, (s)he gets an error (cause (s)he does not have write access on jcr level)