Remove object_collapses and object_bypasses counters

[mjg]

Summary

Spotted during crusade to reduce false-sharing. If someone wants to change them into less unfriendly counters or whatever I'm happy to drop this diff.

[alc]

On a occasion, I do look at these counters. Converting them to an SMP-friendly alternative is probably a worthwhile endeavor.

[kib]

In D12888#268165, @alc wrote:

On a occasion, I do look at these counters. Converting them to an SMP-friendly alternative is probably a worthwhile endeavor.

This is very similar to what I said to Mateusz in the private discussion. In particular, the counters were the key clues in the investigation of bugs fixed by https://www.freebsd.org/security/advisories/FreeBSD-EN-16:17.vm.asc

[alc]

See D13611.

[alc]

Can we abandon this change now?