Fixes #27586
Disable boost multi index safe mode by default when configuring with –enable-debug.
This option can cause transactions to take a long time to be accepted into the mempool under certain conditions; iterator destruction takes O(n) time vs O(1) as they are stored in a singly linked list. See 27586 and the boost docs for more information.
Re-enable it on the CI builds which previously had it enabled.
Re-enable it on the msan fuzz task so that we have fuzz tasks testing with it enabled and disabled in this repo.