releng-scripts now supports LAVA job generation for all boards currently using the legacy job templates.

However, the decision on whether or not to create/submit LAVA jobs is based on the presence of the files in meta-agl/templates/machine/${MACHINE}/test.

Remove these checks from include-agl-run-test-prepare.sh, and instead rely on releng-scripts (utils/create-jobs) to determine if jobs are created based on templates from releng-scripts.