Update buildbucket file location in android_sdk README

Change-Id: I216cef1977664f2ae5e33e6ddf720321961bd806
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4033008
Commit-Queue: John Delaney <johnidel@chromium.org>
Reviewed-by: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1072903}
NOKEYCHECK=True
GitOrigin-RevId: 630cf56211e451faac3095458ab2b26e045d9047