Temporarily add early access warning to welcome pages for EAP 6.1 Alpha

Revert "[JBPAPP-8899] Remove early access warning from welcome pages"

This reverts commit edb861dc95179e459f90a6ba0ce7d7083421da0c.
Revert "Temporarily add early access warning to welcome pages for EAP 6.1 Alpha"

This reverts commit 84c304ec447cb064481cb3a7a3406a39ea713083.
[953282] Update link to portal groups in welcome page