[Chore] Remove refilling loop from test scenarios

Description

Problem: we currently try to keep dedicated moneybag addresses with sufficient funds by refilling them in a loop concurrent with the scenario that uses it. This turned out to be problematic and not very robust, so we want to avoid it after all.

Solution: remove the refilling loop and instead only refill once before the scenario starts. To avoid too many funds from getting stuck in temporary moneybags, most funds get also transferred back after the scenario has completed. Additionally, the refill-balance has been updated in all scenarios to be big enough and with some margin.

Related issue(s)

None, but supersedes !1119 (closed)

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