Butterfly Network: clarify config ConsensusMinerMinPower and PreCommitChallengeDelay

Background

In build/buildconstants/params_butterfly.go, we have two variables which seem to be intended to be configurable for the Butterfly network:

lotus/build/buildconstants/params_butterfly.go

Lines 75 to 76 in a39de1d

    
           var ConsensusMinerMinPower = abi.NewStoragePower(2 << 30) 
        
           var PreCommitChallengeDelay = abi.ChainEpoch(150)

As part of testing F3 I thought it would be useful to adjust these so that I could add participants to F3 in a very short timeframe, without having to wait on the PreCommitChallengeDelay or obtaining the current ConsensusMinerMinPower. I therefor adjusted these down to 256MiB and 10 epochs, but encountered this error when trying to submit:

Error: message ... failed: message execution failed: exit ErrForbidden(18), reason: message failed with backtrace:
00: f01006 (method 34) -- too early to prove sector (18)
(RetCode=18)

Root Cause

It appears that these parameters are actually defined in the actor bundle, not in the params_butterfly.go file. This is evidenced by the build configuration in the builtin-actors repository:
builtin-actors/actors/runtime/build.rs

Impact

The current setup is misleading, as it suggests that these parameters can be easily configured for the Butterfly network, when in reality, they require changes to the actors and generating a bundle for it.

	var ConsensusMinerMinPower = abi.NewStoragePower(2 << 30)
	var PreCommitChallengeDelay = abi.ChainEpoch(150)