fdo#74474: sw: fix Label wizard document creation

Infinite loop in InsertLabEnvText() due to wrong handling of starting '<'.

(regression from fa469b2e00d83459faebe4c1fcb3ea1aac5fb20d)

Change-Id: I1d7ab1b276756bddd87890bb39d3e817330bc6dd
fdo#74474: sw: fix Label wizard document creation harder

The function ReplacePoint() was changed to return a value but not all
call sites were adapted.

(regression from 263153842741d7ce21cc0bf1c5296a55a1138024)

Change-Id: I33efd9ce61611e025dfc76047187826aa0f8dd84