Added 2 new tests related to the SGW database - CBS bucket connectivity

[vipbhardwaj]

There two tests are migrated from the following file from testkit.

It has the tests :

1. test_db_offline_tap_loss_sanity -> test_db_offline_on_bucket_deletion
2. test_multiple_dbs_unique_buckets_lose_tap -> test_multiple_dbs_bucket_deletion

[RIT3shSapata]

I see there's duplicated code for checking if the database is online or offline. There is a dedicated endpoint in SGW to check the status of each database, please consider using that or the endpoint to check the status of each database.

[vipbhardwaj]

This commit addresses the comments from before, plus some modifications to the method for fetching the database status.
Added a class to actually address and accept the response params from the GET /db request and hence using them gracefully.
Plus I have removed min testservers(0) from all the other files as well and changed the handling of the database status method in those files as well.

[RIT3shSapata]

A small nit, you can choose to not implement this, but instead of running an infinite loop, you can add a sleep of 10s, as that is the interval in which SGW scans CB Server and checks if the buckets and configurations exist or not.

[vipbhardwaj]

Cleaned up this PR for the sake of Infra, while #306 is on hold, I think we can get this merged for now?
Moved the lambda func to the test file too. api file is clean with the SGW APIs. @borrrden

[borrrden]

I think after these comments it will surely be small and ok