Machine context reset breaks tests

[Kouteki]

Description

We introduced #2975 to wipe the machine context before each test. The problem is that Onbloc has 90+ tests that now have to be run sequentially, and roughly half of the tests require context to be retained (e.g. block height):

1. TestFunc2 gets affected by behavior in TestFunc1
2. if TestFunc1 changes, we need to change every test code (because for gnoswap we need to check every number(token amount)

Example:

gnoswap staker tc

We should consider introducing an override for machine context.

Related #1982