Disable flaky AutotestPrivateSearchTest.LauncherSearchBoxStateAPITest.

Bug: 1385365
Change-Id: I84ee7a814f11804ced95a685431321db63886ec4
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/4032007


Reviewed-by: Yulun Wu <yulunwu@chromium.org>
Owners-Override: Marijn Kruisselbrink <mek@chromium.org>
Commit-Queue: Marijn Kruisselbrink <mek@chromium.org>
Reviewed-by: Ian Clelland <iclelland@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1072310}