qemuxml2xmltest: Modernize all test cases using QEMU_CAPS_QCOW2_LUKS

qemuxml2xmltest: Modernize all test cases using QEMU_CAPS_QCOW2_LUKS

Modernize 'disk-nvme', 'encrypted-disk-usage', 'encrypted-disk', and
'user-aliases' cases to use DO_TEST_CAPS_LATEST.

This will remove all uses of QEMU_CAPS_QCOW2_LUKS from the test suite.

Since the output files are done via symlinks to input files, the input
files need to be modernized with few auto-added XML bits.

Signed-off-by: Peter Krempa <pkrempa@redhat.com>
Reviewed-by: Pavel Hrdina <phrdina@redhat.com>
Reviewed-by: Ján Tomko <jtomko@redhat.com>