[sync] Break down trusted vault error metrics by migration time

The suffix represents how long ago the user was migrated to the trusted
vault state.

Change-Id: I310e7b3f310f497303a78944f757eb315a05efc9
Fixed: 1081643
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3883437


Reviewed-by: Maksim Moskvitin <mmoskvitin@google.com>
Reviewed-by: Rushan Suleymanov <rushans@google.com>
Commit-Queue: Mikel Astiz <mastiz@chromium.org>
Cr-Commit-Position: refs/heads/main@{#1045348}