feat: update Go Datastore import path (#1261)

* feat: update Go Datastore import path
feat: update Go Bigtable import path

PiperOrigin-RevId: 651776284

Source-Link: https://github.com/googleapis/googleapis/commit/b8eed55ae5a9bf62d0cdb90b10b92dc06c37cd12

Source-Link: https://github.com/googleapis/googleapis-gen/commit/9d7fe2c488e87671e686e3a19aa8cf4f071e806a
Copy-Tag: eyJwIjoiLmdpdGh1Yi8uT3dsQm90LnlhbWwiLCJoIjoiOWQ3ZmUyYzQ4OGU4NzY3MWU2ODZlM2ExOWFhOGNmNGYwNzFlODA2YSJ9

* 🦉 Updates from OwlBot post-processor

See https://github.com/googleapis/repo-automation-bots/blob/main/packages/owl-bot/README.md

---------

Co-authored-by: Owl Bot <gcf-owl-bot[bot]@users.noreply.github.com>