Add switch for defining mta.yaml filename

[yutaoj]

Before submitting a pull request, please ensure the following:

Description

Please explain the changes you made.

Add a link to the design (if applicable).

Checklist

• Code compiles correctly
• Relevant tests were added (unit / contract / integration)
• Relevant logs were added
• Formatting and linting run locally successfully
• All tests pass
• UA review
• Design is documented
• Extended the README / documentation, if necessary
• Open source is approved

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