Legacy plugin model maintained a map of plugins. This is
not used by the new model. Using this map in the new model
causes incorrect lookup of plugins. This change uses adds
a plugin to the map only if its legacy.
Signed-off-by: Anusha Ragunathan <anusha@docker.com>
Upstream-commit: 8fd779dc28a11d8727d76e9553379b0c854f7c4c
Component: engine