Add e2e integration tests for Postgres and remove 2dc runs

[longquanzheng]

What changed?
Adding postgres to run with integration test suits

Why?
Follow up to a conversation in #3488 (comment)

How did you test it?
It's adding tests

Potential risks
No

Local run succeeded:

docker-compose -f docker/buildkite/docker-compose-local.yml run integration-test-postgres
...
...
"service": "cadence-matching", "logging-call-at": "service.go:115"}
--- PASS: TestSizeLimitIntegrationSuite (14.23s)
    --- PASS: TestSizeLimitIntegrationSuite/TestTerminateWorkflowCausedBySizeLimit (2.44s)
PASS
coverage: 29.0% of statements in github.com/uber/cadence/common/..., github.com/uber/cadence/service/..., github.com/uber/cadence/client/..., github.com/uber/cadence/tools/...
ok  	github.com/uber/cadence/host	546.843s	coverage: 29.0% of statements in github.com/uber/cadence/common/..., github.com/uber/cadence/service/..., github.com/uber/cadence/client/..., github.com/uber/cadence/tools/...
1539.65user 518.08system 10:40.22elapsed 321%CPU (0avgtext+0avgdata 1528492maxresident)
136720inputs+1913456outputs (50major+10853577minor)pagefaults 0swaps

[longquanzheng]

@yux0 since you are removing 2DC code, should I just remove all the 2dc stuff here? so that it will save you some effort to do it in another PR.

[yux0]

are those useless? I assume we don't generate code coverage in integration tests

[longquanzheng]

Yeah I believe so.
And if you look at the list, it doesn't take ndc into account. I don't have permission, would you have help me kick off a run to see how the coverage would change?

[yux0]

@yux0 since you are removing 2DC code, should I just remove all the 2dc stuff here? so that it will save you some effort to do it in another PR.

Thanks. It would be great

[andrewjdawson2016]

LGTM thanks @longquanzheng

[longquanzheng]

@yux0 @andrewjdawson2016 because I don't have permission :( can you help trigger a buildkite when reviewing it?

[coveralls]

Coverage increased (+1.2%) to 68.008% when pulling 30b646b on longquanzheng:e2e-postgres into 8bd97e5 on uber:master.