test: Refactor eets blockchain test flow

[Mdaiki0730]

Proposed changes

• Remove CreateContractWithCodeFormatInExecutionSpecTest (set genesis alloc correctly)
• Remove TestBlockchain
• Rename insertBlocksFromTx to insertBlocks
• Rename decodeTx to decode
• Remove TestHeader and, change it to btHeader
• Use useEthGasPrice to calculate eth gas price (rename useEthGasPrice to calculateEthGasPrice)
• Enable parallel execution of tests
• Comment (config etc...)

Types of changes

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• Bugfix
• New feature or enhancement
• Others

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• I have read the CLA and signed by comment I have read the CLA Document and I hereby sign the CLA in first time contribute
• 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
• I have added necessary documentation (if appropriate)
• Any dependent changes have been merged and published in downstream modules

Related issues

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Further comments

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[ulbqb]

LGTM