compact: also fix segments hints data for lost segment files

The code used to remove the missing segment only from "compact" hints,
but we need to also remove it from "segments" hints.

src/borg/repository.py

@@ -808,7 +808,8 @@ class Repository:
         for segment, freeable_space in sorted(self.compact.items()):
             if not self.io.segment_exists(segment):
                 logger.warning('segment %d not found, but listed in compaction data', segment)
-                del self.compact[segment]
+                self.compact.pop(segment, None)
+                self.segments.pop(segment, None)
                 pi.show()
                 continue
             segment_size = self.io.segment_size(segment)