Runcontrol: understand race condition in blockserver and remove arbitrary wait

In the blockserver code there is a race condition between the IOC starting and runcontrol settings being re-applied. The original issue is https://github.com/ISISComputingGroup/IBEX/issues/4344

As a developer, I would like to understand this race condition properly so that we can remove the arbitrary wait in favour of waiting for what we actually need to happen.

Start by reading the blockserver and runcontrol behavior described here, then review the original issue #4344 for the race-condition context. Determine what event must complete after the IOC starts and runcontrol settings are reapplied. Done means the arbitrary wait is removed and replaced by waiting for that required condition.

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