Add tests to ensure a Beat binary belongs to the correct distribution (Elastic or oss)

[adriansr]

Until elastic/beats#25696, we used the help enroll command in Beats to tell Elastic and oss binaries apart.

Once the enroll feature was removed, we had to remove the checks (#196) we put in place (#105) to ensure each distribution contained the right binary.

In order to keep validating that binaries belong to the expected distribution, we need to find an alternate method to identify the distribution for a Beat binary.