Turn off binary compatibility verifications in dotnet CI pipelines

[mrivera-ms]

As discussed here.

[EricDahlvang]

Does the library we are using have a 'compile compat' option?

[BruceHaley]

PR #4761 is merged. Compatibility verifications can now be turned off by editing in ADO BotBuilder-DotNet-CI-PR-yaml, setting the variable DisableApiCompatibityValidation to true.