This change renames the _v3_to_v2_catalog to _normalize_catalog as
part of the v2 removal effort. Several services still rely on the
converted catalog format, so this change maintains the conversion
but removes the v2 association.
Change-Id: Ic7bca16d8c6211d006fc2ba09dc2ecd83f8955db
Partial-Bug: #1845539
Partial-Bug: #1777177