Use TestContainers instead of OpenTable Embedded PostgreSQL.

[SanjayVas]

Since Embedded PostgreSQL switched to using a container in v1.0, there's not much benefit to using that custom solution over TestContainers.

From the Embedded PostgreSQL FAQ:

• Why not just use Testcontainers directly?

  You can, and it should work well for you. The builders, the api compatibility, the wrapping around Flyway - that's the added value. But certainly there's no real reason you can't use TestContainers directly - they have their own Junit4 and Junit5 Rules/Extensions.

[wfa-reviewable]

This change is 

[tristanvuong2021]

Reviewed 7 of 7 files at r1, 1 of 1 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @YuhongWang-Amazon)

[YuhongWang-Amazon]

Reviewed 5 of 7 files at r1, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved (waiting on @SanjayVas)

[SanjayVas]

Going to hold off on merging this until we have a corresponding PR ready in the main repo.