Extend expiration of Printing.CUPS.MigratedMakeAndModel histogram

We're still seeing 100+ events per day, so not yet ready to remove all
this code.

Bug: chromium:1244694
Change-Id: I7bc6d48ce8d6445ec4f01b353d077a9ba1746b05
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3141364


Commit-Queue: Benjamin Gordon <bmgordon@chromium.org>
Reviewed-by: Zentaro Kavanagh <zentaro@chromium.org>
Cr-Commit-Position: refs/heads/main@{#919280}