Move mw.cookie release notes to RELEASE-NOTES-1.24

Leaving it in RELEASE-NOTES-1.23 was an oversight.

Followup to 7c585b5a33d57469d19e9b176f14b84403488b73

Change-Id: If752905a1bae93582b1392a8280dc33eec4ad12e
Merge "Move mw.cookie release notes to RELEASE-NOTES-1.24"