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 for more information.
Re-enable it on the CI builds which previously had it enabled.
Re-enable it on the msan fuzz target so that we have fuzz tasks testing
with it enabeld and disabled in this repo.
Github-Pull: #27724
Rebased-From: 59c8944749