Enable parquet filter pushdown by default

[alamb]

In https://github.com/apache/arrow-datafusion/pull/3380 @thinkharderdev added support for evaluating filters during the parquet scan via the RowIndex mechanism 🎉

This feature is currently enabled via a feature flag, which is disabled by default.

This ticket tracks enabling this feature by default.

Currently known items are:

• [ ] https://github.com/apache/arrow-datafusion/issues/3457
• [ ] Review of parquet test coverage and add additional coverage as needed
• [ ] Enable this feature by default