test: fix flaky test-policy-integrity

Split the test into seven tests so that it doesn't time out.

Fixes: https://github.com/nodejs/node/issues/40694
Fixes: https://github.com/nodejs/node/issues/38088

PR-URL: https://github.com/nodejs/node/pull/40763


Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: Myles Borins <myles.borins@gmail.com>
Reviewed-By: Bradley Farias <bradley.meck@gmail.com>