[sync] Explicitly pass unspecified code origin for local deletions

No behavioral changes, pure refactoring for changes under
['/components/autofill/core/browser/webdata/addresses',
 '/components/autofill/core/browser/webdata/autocomplete']

Note to reviewers: please consider extending these datatypes with the
ability to track where each deletion is coming from, usually by
requiring a base::Location in the public APIs used to issue deletions.
See https://crrev.com/c/5458455 or https://crrev.com/c/5473304 for
reference.

Currently, this code has no information available about where precisely
in the source code the deletion was triggered. Instead of using an
overload of ModelTypeChangeProcessor::Delete() that implicitly uses
DeletionOrigin::Unspecified(), this patch makes the caller more
explicit and passes this value directly.

This CL was uploaded by git cl split.

Bug: 334001702
Change-Id: I28ab25860b564621d05fe6512e9ac8ac5e150add
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5514144
Reviewed-by: Florian Leimgruber <fleimgruber@google.com>
Auto-Submit: Mikel Astiz <mastiz@chromium.org>
Commit-Queue: Florian Leimgruber <fleimgruber@google.com>
Cr-Commit-Position: refs/heads/main@{#1296037}