refactor: Update ES index maps to use same maps of amundsen-common

[Wonong]

Summary of Changes

• Added amundsen-common package to requirements.txt
• Deleted python 2.7 in extras_require in setup.py since python_requires only allow python versions higher than 3.6
• Deleted elasticsearch_constants.py and updated related codes to use ES index map of amundsen-common

Tests

Execute sample_data_loader following this guide(https://github.com/amundsen-io/amundsen/blob/master/docs/installation.md#bootstrap-a-default-version-of-amundsen-using-docker)
and it works successfully

Documentation

N/A

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[feng-tao]

thanks!