fdo#71077 wrong tips for some calc functions

Calc functions with name X where also calc functions with
name XY exist show the tip for the first XY function
instead of the X function as soon as the '(' is typed in the cell.
This fixes that.

Change-Id: I4dc6280db904765e40eacfe33be6a7e25e84ae79
Reviewed-on: https://gerrit.libreoffice.org/8143
Reviewed-by: Caolán McNamara <caolanm@redhat.com>
Tested-by: Caolán McNamara <caolanm@redhat.com>