Revert "refactor(router): cleanup to navigation stream for readabilit…

[kara]

Reverting #25740 while we look into test failures within Google. (Squashed into 1 commit)

[mary-poppins]

You can preview 9c21b7e at https://pr26060-9c21b7e.ngbuilds.io/.

[ngbot]

I see that you just added the PR action: merge label, but the following checks are still failing:
     status "ci/circleci: integration_test" is failing
     missing required labels: PR target: *

If you want your PR to be merged, it has to pass all the CI checks.

If you can't get the PR to a green state due to flakes or broken master, please try rebasing to master and/or restarting the CI job. If that fails and you believe that the issue is not due to your change, please contact the caretaker and ask for help.

[angular-automatic-lock-bot]

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