With this commit we rename `node.store.allow_mmapfs` to
`node.store.allow_mmap`. Previously this setting has controlled whether
`mmapfs` could be used as a store type. With the introduction of
`hybridfs` which also relies on memory-mapping,
`node.store.allow_mmapfs` also applies to `hybridfs` and thus we rename
it in order to convey that it is actually used to allow memory-mapping
but not a specific store type.
Relates #36668
Relates #37070
75f3443c62