chore: add seal to workaround performance issue

[leodemoura]

This PR adds seal commands at grind_ite.lean to workaround expensive definitionally equality tests in the canonicalizer. The new module system will automatically hide definitions such as HashMap.insert and TreeMap.insert which are being unfolded by the canonicalizer in this test.
This PR also adds a profileItM for tracking the time spent in the grind canonicalizer.

[leanprover-community-bot]

Mathlib CI status (docs):

• ❗ Batteries/Mathlib CI will not be attempted unless your PR branches off the nightly-with-mathlib branch. Try git rebase a54872f5f64c9e8e0b89276384a2793b008b0078 --onto d5060e9e66aee1eee60bbeeea8ae9b9c94e29a47. You can force Mathlib CI using the force-mathlib-ci label. (2025-05-25 01:00:51)