Updates the commit the `components-repo-unit-tests` job runs
against. The goal is that we run against a revision that at
least contains: https://github.com/angular/components/pull/19336.

The new commit contains fixes for a flaky test in the datepicker that we
saw failing in the components-repo-unit-tests job too:
https://app.circleci.com/pipelines/github/angular/angular/15359/workflows/27ffae7c-a7b8-46a3-9c9e-6dd22ca4734d/jobs/712643.

Additionally, with this commit, the components repo unit tests job will
use TypeScript 3.9.2, so we can re-enable the job in another commit.

PR Close #37176