[Password Manager] More precise errors for failure on LinuxPasswordsMigrationToEncryptionStatus

When migrating away from the native backend, the most common cause of
failure are operations on the temporary database. I've split the error
code for further insight.

Bug: 571003
Change-Id: I382e62ebeb9c85306526bcd6978a1aa41a5e79fc
Reviewed-on: https://chromium-review.googlesource.com/c/1411609
Reviewed-by: Christos Froussios <cfroussios@chromium.org>
Reviewed-by: Vasilii Sukhanov <vasilii@chromium.org>
Commit-Queue: Christos Froussios <cfroussios@chromium.org>
Cr-Commit-Position: refs/heads/master@{#623182}
4 files changed