[microTVM] Clean-up test_crt.py and add to pylint

[alanmacd]

• normalize test_crt.py temporary directory usage
• remove test_crt.py unused code and variables
• fix test_crt.py to pass pylint and add to pylint script

[tvm-bot]

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• cc @gromero, @leandron, @mehrdadh, @mkatanbaf _{See #10317 for details}

_{Generated by tvm-bot}

[mehrdadh]

Thanks @alanmacd!!