XLSX Pivot Export - Initialize Pivot Table with Small Area Ref (#50060) (#50111)

* XLSX Pivot Export - Initialize Pivot Table with Small Area Ref

This PR changes the native pivot export so that we first initialize the pivot table with an area ref that's only the
first 2 rows. Prior, I used `AreaReference/GetWholecolumn` which had the side effect of using lots of memory.

I think this is related to how the Pivot Table's Cache is built up as you add rows/cols to the pivot definition. So,
if you keep the area ref only as wide as the number of columns in the raw data, and just 2 rows, then the cache can
stay small.

After adding row/column data to the pivot table, you can then modify the area ref to be all rows in the relevant
columns (`A:E` for example).

This keeps the pivot-table object much smaller in size.

* need the extra xml schemas to get this to work

I'd like to try find a way around including this extra dep, it's a 13mb jar (ish), and I think that's a little bigger
than I'd like

* oops, didnt mean to have this in

* Add test for pivot table initialization being fast and lean on memory

* remove time based assertion, add comments in impl

* cljfmt

* fix test

* Pesky little whitespace

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Co-authored-by: adam-james <21064735+adam-james-v@users.noreply.github.com>
Co-authored-by: Oleksandr Yakushev <alex@bytopia.org>