Sgw multi cbs test migration

[vipbhardwaj]

The test being migrated is this

There are a lot of changes to the infra to support the multi-CBS topology, and I have changed the SGW topology.json to have 2 cbs' as well.

There are some changes to have both Private and Public IP to be served based on the need, since TDK requires to communicate via Public IP but some APIs use Private IP and the SGW <-> CBS comunication happens via private IP since they are a part of the same VPC in AWS up there. ☁️

I've also added a miniscule change of reducing the num_docs of test_purge fromm 1000 -> 100, to match the others, and after the continuous pain that it, unlike the other tests, takes more than half an hour due to 10x the docs to jiggle with.

[borrrden]

In addition the sync gateway class I think needs some more thinking (messaged offline)

[vipbhardwaj]

I've addressed the issues in the sub-comments, as to the SGW related parent comment issue, I am working on it and will merge the appropriate code in the PR#322 : sgw-refactoring
As that is the one catering to the SGW based class changes.
Re requesting review : @borrrden , @RIT3shSapata

[borrrden]

Let's start with this. Also this PR has a bunch of sync gateway changes. If they are needed lets focus on the other PR first which is for those changes.

[vipbhardwaj]

I resolved the merge conflicts since the #306 got merged and now I think this PR is ripe to be merged too 🍓 ✅

[vipbhardwaj]

@borrrden @RIT3shSapata I've added another test to the same file hence requesting reviews again.

TDK changes :

1. Changed the configure-nodes script to have it add the kv, n1ql ports too since they SDK ops were targeting out
2. As to why now? Why not before?
3. I've changed the topology to have 3 CB-clusters and hence 3 SG-nodes serving the 3 CBs each.
4. To keep the change backwards compatible, I've added servers in this way :
5. CBS initially only needed 2 nodes in a single cluster, so now I've added more 2 servers, each being a cluster in its own, hence there are 3 CBS CLUSTERS now, CLUSTER 1 = 2 node, CLUSTER 2 and 3 = 1 node each
6. For these 3 clusters to be served by SGWs, we only need 1 SG server per cluster. Hence I added two more SG servers too, so total of 5 SG nodes where 3 serve CLUSTER 1, and then the 4th and 5th serve CLUSTER 2 and 3 resp.

TEST changes :

Added a test for collection based mapping across clusters.
This is the test that's been migrated. Basically 3 docs added per SG targeted to specific collections in each CLUSTER's buckets.
Then ISGR is done, once push, once pull, and then it's verified that the docs got replicated correctly.

[RIT3shSapata]

The tests look good, I just have a few nits about the description of the tests and code cleanliness

[vipbhardwaj]

Guys please give a final review for this please 😢