[WIP] Remove internal bazel build and Circle CI

[augray]

No description provided.

[augray]

This test was:
(a) not actually testing what it claimed to be testing
(b) not claiming to test something that I think we want to implement for now
(c) causing pytest to fork such that subsequent tests were computed twice

Thus I'm removing it.

Explanation:
(a) it claims to be confirming that if the body of a Sematic func forks and doesn't clean up one of the processes by an explicit exit, the Sematic post-processing will only occur for one of the processes. However, the way that it attempts to test this is simply by confirming that the return value from the func is what's expected. But as written, that return value will be the same for both forks, regardless of whether Sematic post-processing occurs. Thus it passes even if the behavior it wants to guard against is actually occurring.
(b) enforcing the behavior this is trying to guard against would require some fairly fiddly and race-condition-prone logic that I don't think we want to address at this moment. It should also be a fairly rare edge-case anyway, and generally will be innocuous even if it occurs.
(c) since neither fork is cleaned and the fork is from the interpreter running pytest, pytest itself continues to run in both forks. This wasn't much of an issue with bazel as the test runner because it ran each test file in its own sandboxed interpreter. So the only duplication was at the test file level, not at the whole test-suite level.