[Digital credentials WPT] Fix non-fully-active test
This CL switches the test to use navigator.credentials instead of
navigator.identity. navigator.credentials handles ScriptState::ContextIsValid() == false
BUG=343991289
Change-Id: If04237247ada802b6cd2447bc6336422658a94c6
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5882341
Commit-Queue: Peter Kotwicz pkotwicz@chromium.org
Reviewed-by: Ken Buchanan kenrb@chromium.org
Cr-Commit-Position: refs/heads/main@{#1359564}