txpool: Accept transaction from new sender with better price

[tnasu]

Proposed changes

Change behavior when the TxPool capacity is exceeded (from the LegacyPool of Geth)

• ASIS: Simple FixedSelection by size
  • https://github.com/kaiachain/kaia/pull/391/files#diff-4a20f160f5182ec35d76a3566352906f577b84fbf3b242b922c4d2fc9c219cd7L1386-L1388
• TOBE: FixedPriorityQueue by gas price
  • Don't accept by lower price
    • https://github.com/kaiachain/kaia/pull/391/files#diff-4a20f160f5182ec35d76a3566352906f577b84fbf3b242b922c4d2fc9c219cd7R1050-R1055
  • Kick out by other higher price
    • https://github.com/kaiachain/kaia/pull/391/files#diff-4a20f160f5182ec35d76a3566352906f577b84fbf3b242b922c4d2fc9c219cd7R1096-R1103
    • And when it happens to have too many kicks out, which is reorg, it also raises an error
      • https://github.com/kaiachain/kaia/pull/391/files#diff-4a20f160f5182ec35d76a3566352906f577b84fbf3b242b922c4d2fc9c219cd7R1057-R1064

And, TxPool priced heap treats only remote for dropping/discarding under price tx without distinction between local/remote(Remove local from TxPool priced heap)
Ref: https://github.com/ethereum/go-ethereum/pull/21478/files

Types of changes

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• Bugfix
• New feature or enhancement
• Others

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Related issues

Further comments

[tnasu]

@hyeonLewis @yoomee1313 I considered your feedback, and I removed local from TxPool priced heap. Please review it again. Thanks.

[tnasu]

@hyeonLewis, @yoomee1313, I reconsidered that my additional commit has side effects. At this time, I focused on maintaining local consistency.