Make Servicechain tx fee hardfork

[JayChoi1736]

Proposed changes

• Following Fix reward distribution and getRewards API on deferredTxfee = false #1886, this problem can be corrected with a single hard fork for service chains.
• In formal states, the deferredTxfee problem has been solved in only after MagmaHardfork
• After this PR, servicechain operator can solve the problem with a single hardfork: ServiceChainTxFeeHardfork (like "serviceChainTxFeeCompatibleBlock":3600 in config),

Test Result

• Test Setting
  • block reward : 1000000000
  • txFee reward : 5250000000000000
  • policy : simple(=0) or not(=2)
  • test when: before serviceChainTxFeeHardfork, after serviceChainTxFeeHardFork and before MagmaHardfork, and after MagmaHardfork
  • check KlayGetRewards result, and actual balance changes in RewardBase and Proposer account

Policy	before PR	after PR
not simple
simple

• Result Analysis
  • After ServiceChainTxFeeHardfork, txfee goes to only RewardBase, and not duplicated

Types of changes

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• Bugfix
• New feature or enhancement
• Others

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• Lint and unit tests pass locally with my changes ($ make test)
• I have added tests that prove my fix is effective or that my feature works
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Related issues

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Further comments

If this is a relatively large or complex change, kick off the discussion by explaining why you chose the solution you did and what alternatives you considered, etc...

[hyunsooda]

Apologies for the delayed input. The current name appears ambiguous in its purpose. Have you considered renaming it for clarity, perhaps as 'servicechain-consensus-rewardfix'?

[JayChoi1736]

Thank you.
I changes hardfork name to ServiceChainRewardFix in a96d57c
However, I will leave this conversation open to hear the opinions of other reviewers