fix: increase maxHeartbeats in isDefEqProjIssue test for the new compiler (#8561)

This PR increases maxHeartbeats in the isDefEqProjIssue test, because
when running under the new compiler the `run_meta` call includes the
allocations of the compiler itself. With the old compiler, many of the
corresponding allocations were internal to C++ code and would not
increase the heartbeat count.