Migrate Optimizer tests to insta, part3 (apache#15893)

* migrate tests in `push_down_filters.rs` to use snapshot assertions

* remove unused format checks

* Revert "remove unused format checks"

This reverts commit dc4f137.

* migrate `assert_eq!` in `push_down_filters.rs` to use snapshot assertions

* migrate `assert_eq!` in `push_down_filters.rs` to use snapshot assertions

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Co-authored-by: Dmitrii Blaginin <dmitrii@blaginin.me>

Author: qstommyshu