std::atomic implicitly deletes copy and move, so a class holding a Counter is
non-copyable when telemetry is compiled in. Compiled out, Counter was an empty
type with no such member, which would have made that same owner freely
copyable in one build only -- the per-configuration API difference these
utilities exist to avoid.
Declare copy and move deleted so both builds agree, and assert it
unconditionally in the tests.
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