Updates the material-unit-tests job commit SHA to the most recent
commit at the time of writing. The goal is to run the unit tests
with https://github.com/angular/components/commit/6ae74a0eb21268d4b107a052a8cf8ae63078bf99
that improved stability of a few menu tests that were flaky.

e.g. https://circleci.com/gh/angular/angular/564650

PR Close #34430