[lldb] Re-enable TestVSCode_disconnect on Darwin

The test was disabled because it failed on the sanitized bot. I'm not
able to reproduce that locally. The test uses timeouts which could
explain why it was failing in the past.

Let's re-enable it and see what happens. If it fails again on
GreenDragon, rather than disabling it on Darwin altogether, we should
either increase the timeouts or skip it when run under ASan.