Enable test that verifies high tapped amount. (#6913)

Fixes #2336

Since #2336 was filed, #4113 deprecated `scan_txlog.py` and removed the code that ran it, but #5922 added a max tap amount of 100,000,000, so the existing test code failed with a "requirement ... was not met" error. This updates the test code to instead tap the max amount.

Signed-off-by: Matt Dziuban <mrdziuban@gmail.com>