[Chore] Automatically refill step moneybags

Description

Problem: Since 1d9738f6, each CI step that runs network tests has its own moneybag, which is filled before the scenario is started. This can be quite inconvenient, because the initial balance may need to be adjusted in the future. Also, such an approach is inconvenient for large scenarios, because it's hard to come up with a sane initial balance.

Solution: Automatically refill step moneybag while chain tests are running.

Related issue(s)

https://issues.serokell.io/issue/TM-628

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