flake: extra 1000000 in the provision pool

[turadg]

Working on #88 I often get an error in upgrade-8 checking the provision pool balance:

agoric-3-proposals/proposals/16:upgrade-8/use.sh

Lines 12 to 15 in e303fd0

	# ensure there's nothing in the provision pool
	BALANCE="$(agd q bank balances agoric1megzytg65cyrgzs6fvzxgrcqvwwl7ugpt62346 -o json)"
	test_val "$(echo $BALANCE | jq -r '.balances | length')" "0" "provisionpool balance should be empty but was $BALANCE"

In https://github.com/Agoric/agoric-3-proposals/actions/runs/7809408199/job/21301178798 we saw something similar during upgrade-10:

#1446 [use-upgrade-10 linux/amd64 use-upgrade-10 3/3] RUN ./run_use.sh 34:upgrade-10
#1446 7.297   ✘ [fail]: Pre Vault tests Test failed via `t.fail()`
#1446 7.321   ─
#1446 7.321 
#1446 7.321   Provision pool has right balance
#1446 7.321 
#1446 7.321   pre.test.js:87
#1446 7.321 
#1446 7.321    86:                                               
#1446 7.321    87:   t.is(result.balances[0].amount, '19000000');
#1446 7.321    88: });                                           
#1446 7.321 
#1446 7.321   Difference (- actual, + expected):
#1446 7.321 
#1446 7.321   - '18000000'
#1446 7.321   + '19000000'

The amount may just be a coincidence, or due to some race. Regardless there's some flakiness.