After PR #8095 - Nexthop selection strategies no-longer marks down hosts for self detection.

[jrushford]

Since PR #8095 Clean up Machine implementation for issue #4159, Next hop selection strategies and probably parent selection no-longer marks down hosts defined in strategies.yaml or parent.config as down for self detection if the host has the same hostname or IP address as self cache on startup. The Machine::is_self() function is not returning true that the machine is its self.

[jrushford]

@SolidWallOfCode it appears to me that when NextHopSelectionStrategy calls Machine::is_self(), the unordered_set machine_id_strings is empty.