Prerender: Fix speculation-rules/prerender/cookies.html

Before this CL, the test was failing due to the undefined cookieStore
attribute. This was caused by that the attribute is only exposed to the
secure context but the test was running on http.

This CL renames the test to cookies.https.html so that the test can run
on https.

Bug: n/a
Change-Id: I9479c7a7aa634ca6059cfe0cd1e070d3c7489300
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3963595
Reviewed-by: Ken Okada <kenoss@chromium.org>
Commit-Queue: Hiroki Nakagawa <nhiroki@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1061012}
diff --git a/speculation-rules/prerender/cookies.html b/speculation-rules/prerender/cookies.https.html
similarity index 100%
rename from speculation-rules/prerender/cookies.html
rename to speculation-rules/prerender/cookies.https.html