Activation page doesn't show notices anymore

[liongrass]

The activation page in bp-legacy templates no longer displays a template notice when an invalid activation key is entered.

This issue appears to originate from a recent change in the bp_core_setup_message() function, introduced between versions 14.1.0 and 14.3.4, which now returns early if the user is not logged in.

Because the activation page is specifically intended for users who are not logged in, this change prevents any notice from being shown when an invalid key is submitted.