[HUDI-8106] Use the new filegroup reader for the metadata table

[jonvex]

Change Logs

use new fg reader for mdt

Impact

transition to fg reader for more use cases

Risk level (write none, low medium or high below)

medium need to test more

Documentation Update

N/A

Contributor's checklist

• [ ] Read through contributor's guide
• [ ] Change Logs and Impact were stated clearly
• [ ] Adequate tests were added if applicable
• [ ] CI passed

[hudi-bot]

CI report:

• 1ccf0f8660a8c54dd4f7920f828900b96f566785 Azure: FAILURE

Bot commands

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• @hudi-bot run azure re-run the last Azure build