Revert "Remove the parsing limit in QSvgHandler"

This reverts commit b85a6475bffa4dbbc310e17ca9de5e745e8975e8.

Reason for revert: There are other functions that rely on recursion for
calculations. This change removes the safeguard that prevented this from
happening.

The test was modified to expect failure on 2048 nested elements or more,
since the parsing limit is reintroduced in this revert.

Task-number: QTBUG-148407
Pick-to: 6.12 6.11
Change-Id: Id2ffe1849da5eccd5e9c6036bac1b2120e60a47b
Reviewed-by: Eskil Abrahamsen Blomfeldt <eskil.abrahamsen-blomfeldt@qt.io>