Split up backend/sysmeta header/footer preference tests
Split up backend/sysmeta header/footer preference tests

The change in preference to the Related-Change is simply to prefer
sysmeta overrides in the headers to backend overrides in the footers:

Before:
sysmeta footers > backend footers > sysmeta headers > backend headers

After:
sysmeta footers > sysmeta headers > backend footers > backend headers

This change just breaks up the tests to try to make it more obvious
what already worked and what has changed.  The justification seems to
be that overrides in sysmeta headers only work on policies that don't
send backend footers, but sysmeta overrides should always have a
higher preference than backend overrides.

Related-Change: Idb40361ac72da51e1390dff690723dbc2c653a13
Change-Id: I074fbecb6440fb1d04279cd892d38d2acc44b47d

larsbutler/swift,openstack/swift,nadeemsyed/swift,smerritt/swift,redbo/swift,prashanthpai/swift,nadeemsyed/swift,nadeemsyed/swift,redbo/swift,matthewoliver/swift,psachin/swift,psachin/swift,swiftstack/swift,larsbutler/swift,notmyname/swift,hurricanerix/swift,hurricanerix/swift,matthewoliver/swift,prashanthpai/swift,hurricanerix/swift,nadeemsyed/swift,smerritt/swift,tipabu/swift,notmyname/swift,smerritt/swift,psachin/swift,matthewoliver/swift,clayg/swift,tipabu/swift,clayg/swift,notmyname/swift,clayg/swift,matthewoliver/swift,smerritt/swift,openstack/swift,openstack/swift,clayg/swift,hurricanerix/swift,notmyname/swift,psachin/swift,swiftstack/swift,openstack/swift,swiftstack/swift,tipabu/swift,tipabu/swift