Only run hotswap integration tests for postgres
Only run hotswap integration tests for postgres

- There is no need to run this for each database group

[#155019024](https://www.pivotaltracker.com/story/show/155019024)

Signed-off-by: Michael Xu <9a9f0f9e4cafa7274ac4427113dff9772742c003@pivotal.io>

barthy1/bosh,barthy1/bosh,barthy1/bosh,barthy1/bosh