If operator has configured read-only 'http' store in multiple stores and while
importing or copying existing image in multiple stores if user has specified
--all-stores true then depending on `allow-failure`; if it is True then image
is imported/copied to other stores than http or if it is false then image can
not be imported/copied to other stores as well. Aslo, new image property
`os_glance_failed_imports` shows `http` as failed store.
Excluded `http` store from the list of stores for import/copying workflow
if user specifies --all-stores as True.
Change-Id: I2ad41022aa709491881e78129708da0ccc25f4f6
Closes-Bug: #1881958
f7b1631190