Remove all references to the Conduit ConnectionLog

Summary:
Ref T5955, T9980, T9982.

We currently store two types of Conduit logs: connection logs and method logs.

Originally, Conduit worked like web logins: you'd call conduit.connect and then get a session back. This approach still works, but new clients don't use it and it will probably stop working eventually after T5955 is further along.

There was no real reason for things to work like this and no other API in the world does, I think it was just slightly easier to implement back in 2011.

This table was used to group up related calls in a UI long ago, I think, but that got deleted at some point. In any case, it serves no purpose in modern Phabricator.

Test Plan: grep

Reviewers: chad

Reviewed By: chad

Maniphest Tasks: T5955, T9980, T9982

Differential Revision: https://secure.phabricator.com/D14780