CA-37151: If a SIGTERM/SIGINT is received during metadata backup we should tidy up properly
CA-37151: If a SIGTERM/SIGINT is received during metadata backup we should tidy up properly

This means run cleanup() if the signal is received and in cleanup block the signal so that
a second SIGTERM/SIGINT doesn't cause a problem.

Also, in cleanup(), if we have an uninitialised vdi (e.g. because we've just created it but
have not yet mkfs'd it) then we ought to delete the vdi.

Signed-off-by: Alex Zeffertt <c17d99cd726ca910f8a9b30d177bb04074ebef1c@eu.citrix.com>

djs55/xcp-networkd,johnelse/xcp-rrdd,djs55/xcp-rrdd,koushikcgit/xcp-networkd,sharady/xcp-networkd,koushikcgit/xcp-networkd,johnelse/xcp-rrdd,djs55/squeezed,djs55/xcp-networkd,simonjbeaumont/xcp-rrdd,koushikcgit/xcp-rrdd,robhoes/squeezed,koushikcgit/xcp-rrdd,simonjbeaumont/xcp-rrdd,sharady/xcp-networkd,koushikcgit/xcp-rrdd,djs55/xcp-rrdd