De-flake testRedirectFromCctEarlyNav

When using a local test server, the redirect to an app can come so fast
that the redirect finishes before native initialization finishes,
leading us to close the tab before it ever gets attached to the tab
model (and failing to close the tab).

Very unlikely this gets hit in the wild (no hits of the assertion on
Canary over the past few months), but fixing just in case.

Bug: 422303953
Change-Id: I04ca2dea822ed7c1fc57506e5aa204d12dd9f831
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6925943
Reviewed-by: Jinsuk Kim <jinsukkim@chromium.org>
Commit-Queue: Michael Thiessen <mthiesse@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1513782}