CookieStore: Remove [Replaceable] from IDL

Bug: 1124891, 1125194
Change-Id: Ia8346f1b68b3f0726662b8dd37de66cce0b9e490
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2393182


Reviewed-by: Victor Costan <pwnall@chromium.org>
Commit-Queue: Victor Costan <pwnall@chromium.org>
Cr-Commit-Position: refs/heads/master@{#805189}