The 5.5/5.6 concurrency runtime in the concurrency backdeploy library
just doesn't have the pieces necessary to emit the desired error
message. Disabling it in that environment.
Commit afc5116ef0 added the support to track re-used continuations.
* Enable running tests from test/Concurrency/ directory in freestanding/minimal presets
* Mark failing Concurrency tests as XFAIL/SKIP on freestanding/minimal