Convert P6 tests to also run for P7 and onwards

[limemloh]

Purpose

Prior to this PR, numerous of our tests are only targeting protocol version 6, this PR changes this such that these tests are generalized to run against every protocol version starting from P6 and onwards.

Changes

• No changes are intended by this PR besides generalizing the tests, the only exception is a test related to account nonce https://github.com/Concordium/concordium-node/pull/1111/files#diff-176f6e3e32412c792f8e0873ce966e99076d1be8da6a228d9226d6b87301fbefR760

Checklist

• [ ] My code follows the style of this project.
• [ ] The code compiles without warnings.
• [ ] I have performed a self-review of the changes.
• [ ] I have documented my code, in particular the intent of the hard-to-understand areas.
• [ ] (If necessary) I have updated the CHANGELOG.