This sets a default timeout of 3 minutes on CLI integration tests. This
is because these tests call into the CLI and execute queries, so these
are expected to take a lot longer than the default 5 seconds. This
allows us to remove all the individual `jest.setTimeout` calls with
different values from the test files.
This removes all CodeQL CLI version constraints for unsupported CLI
versions (< 2.7.6). The oldest supported CLI version is 2.7.6 since GHES
3.3 recommends using CodeQL CLI 2.7.6.