Cleanup of help texts. (#14723)

All help texts were removed, which fell into one of the categories below:

1. there is sublabel for the menu item and it contains same or better text.
Such texts and translations should be maintained as sublabel, located in
msg_hash_xx.h. Since PR#14714, sublabel will be displayed as help if present.

2. it could be confirmed that this help text is currently not shown anywhere.
Examples are deprecated features (like DEBUG_INFO) or fully removed (like
CONFIRM_EXIT)

Some enum labels were just fixed to enable display.

Information can also be updated in several places, but let's keep it separate.

Author: zoltanvb