[Autofill Assistant] Fix client status number.

Use 20 instead of 15 for reporting INVALID_SELECTOR errors, as 15 has
already been allocated, server-side.

Bug: b/129254215
Change-Id: Iafadd9484776d94e622f64f7db819c324bb581aa
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1578558
Reviewed-by: Clemens Arbesser <arbesser@google.com>
Commit-Queue: Stephane Zermatten <szermatt@chromium.org>
Cr-Commit-Position: refs/heads/master@{#653995}
1 file changed