Close#3366. Roll back the test structure to the one that it has before
d2a7162217. Add one extra block to ensure
that main transaction won't be finilized. Add NVB increment slippage to
avoid race between the first fallback acceptance and block acceptance.
Add NVB increment slippage to the rest of fallbacks for test structure
unification.
Signed-off-by: Anna Shaleva <shaleva.ann@nspcc.ru>
f95004ad83