Re-add isolated tcprouting tests with a standalone option

[geofffranks]

Are you submitting this PR against the develop branch?

Yes

What is this change about?

Re-implements the #474 to play nicer with other environments. Adds a retargeting step in isolation segment after each calls to ensure other tests running get targeted to the correct space. Enables testing of TCP routing to isolated diego cells.

Please provide contextual information.

Re-implements #474

What version of cf-deployment have you run this cf-acceptance-test change against?

latest

Please check all that apply for this PR:

• introduces a new test --- Are you sure everyone should be running this test?
• changes an existing test
• requires an update to a CATs integration-config

New property (optional, default off) to run include_tcp_isolation_segments. If enabled, requires include_isolation_segments and isolation_segment_name

Did you update the README as appropriate for this change?

• YES
• N/A

If you are introducing a new acceptance test, what is your rationale for including it CATs rather than your own acceptance test suite?

CATs validates the proper configuration of isolated diego-cells in conjunction with a shared tcp router. It's best to test this in a scope responsible for the shipped configuration of both components.

How should this change be described in cf-acceptance-tests release notes?

Enables optional testing of TCP routing on isolation-segments via the include_tcp_isolation_segments config property.

How many more (or fewer) seconds of runtime will this change introduce to CATs?

300s when enabled

What is the level of urgency for publishing this change?

• Urgent - unblocks current or future work
• [ x ] Slightly Less than Urgent

Tag your pair, your PM, and/or team!

[davewalter]

Thanks for the updated PR @geofffranks! Looks good.