Deflake grpclb test

Propagate (some) signals to subprocesses in json_run_localhost

Fix TCP shutdown path on Windows

Break infinite connection retry loop

Previously, we'd keep retrying a connection until the channel closed.
With this change, we only retry connecting *if there's a watcher on the
subchannel connection state*. This ultimately means that if the
lb_policy doesn't care if the subchannel connects, it'll stop trying.

Basic config for internal CI (take 2)

Draft of C# server reflection

- we were treating an int as atomic, which is dubious at best
- it was possible to shutdown while an accept was being handled, and
process that shutdown accept before the real accept finished, leading to
a use-after-free up the stack

Revert "Test credentials provider update"

Fix TSAN race on adding a reclaimer

Test credentials provider update