op-e2e: Improve parallelism in op-e2e FP tests

The op-e2e fault proof tests that utilize cannon use at most 8 executors to avoid OOM when running on the latitude box. This is a heavy handed approach that leaves alot of parallelism that may still be available on that box.
Let's use a better method for limiting memory usage in op-e2e tests.

Locate the op-e2e fault proof tests that use cannon and inspect how their executor limit is set; no file or test path is provided. Review the latitude box's memory constraints and validate that the tests can use more safe parallelism without causing OOM.

Written by the indexing model from the issue text.