revert "vlookup - optimize SC_EQUAL and NOT_EQUAL." (tdf#139612)

revert "vlookup - optimize SC_EQUAL and NOT_EQUAL." (tdf#139612)

That commit breaks lookup when the  "Search criteria = and <> must
apply to whole cells" option is disabled, as it enforces whole cell
checking regardless of the option. Given that the option is enabled
by default in LO ('SearchCriteria' in Calc.xcs) and it's what
MSOffice does as well, and this default gives good performance
regardless of the option, I don't understand the purpose
of the commit. Possibly it was based on a document where somebody
disabled the option and then indeed got worse performance.
Solution: Don't do that :).

This reverts the code parts of a953fa1c0f6a40a08859570516c511f3a841 .
The test I've kept but switched to ensure that partial matching
does work if the option to match whole cells is disabled. I've
also changed the tooltip for the option to mention performance
and not suggest that off is the default.

Change-Id: I56d7b6e7b8e9f0622f7ad6d447daf56c3b705a7e
Reviewed-on: https://gerrit.libreoffice.org/c/core/+/125267
Tested-by: Jenkins
Reviewed-by: Mike Kaganski <mike.kaganski@collabora.com>
Reviewed-by: Luboš Luňák <l.lunak@collabora.com>