Concrete Playback playback subcommand picks up regular unit tests and fails to compile

[jaisnan]

When there are other unit tests present, running cargo kani playback -- kani_concrete_playback_harness_i64_13477596495325479973 for example, gives compilation errors that are picked up from unit tests unrelated to kani. The command breaks completely and displays an empty output.

[celinval]

After discussing offline, the problem seems to be with the integration tests, not with the playback back mode. The integration tests were using functions that were not defined when kani config was set. We can provide options for the user to disable the integration tests though.