The delete policy can only be set for POP3 accounts. However, the delete policy
is used for all legacy accounts (that includes IMAP). As such, we need to make
sure IMAP accounts also have their policy set; even though the setting is not
configurable by the user.
The delete policy does not mean anything for Exchange accounts, so, we do not
need to modify the account setup code for them.
bug 3074164
Change-Id: Iab10d2997404b3b0c10a60a64fb652540c0d2d1a