[3.14] gh-142145: Avoid timing measurements in quadratic behavior test (gh-143105...

[3.14] gh-142145: Avoid timing measurements in quadratic behavior test (gh-143105) (#143139)

Count the number of Element attribute accesses as a proxy for work done.
With double the amount of work, a ratio of 2.0 indicates linear scaling
and 4.0 quadratic scaling. Use 3.2 as an intermediate threshold.
(cherry picked from commit 57937a8e5e293f0dcba5115f7b7a11b1e0c9a273)

Co-authored-by: Sam Gross <colesbury@gmail.com>