Given the instance.uuid lock taken on the remote compute, calls to
reserve_block_device_name can take a large amount of time to complete
when attaching multiple volumes. To help avoid timeouts during such
attempts this change switches to using the long_rpc_timeout for the
overall timeout for each call.
Related-Bug: #1844296
Change-Id: I17e0e45117a3312c11d6c7f2762dd416b6067979
(cherry picked from commit 648c05f7be)
(cherry picked from commit f9a1bc7105)
(cherry picked from commit e858ab3bbe)