[schema] fix composite deletion handling
Do not delete component entities if the composite is not deleted in
the same transaction.
Deletion semantics are thus: if the composite is deleted, the
components are deleted.
Closes #3463112.
addressbook
basket
blog
book
calendar
comment
company
email
file
folder
i18ncontent
keyword
link
mailinglist
person
tag
timeseries
vcsfile