LU-9544 utils: set -P if missing in 'set_param -d'

LU-9544 utils: set -P if missing in 'set_param -d'

The -P option to lctl set_param will now be added if
the -d option (for delete) is specified by itself.

As described in the ticket, if a value is erroneously supplied when
using -P and -d then instead of being deleted, the parameter is
set to the old value with a trailing '='. A non-regression test
has been created to verify that this isn't happening.

wait_update_cond and wait_update were modified to avoid unresolved
errors from throwing an unwanted errnum during the wait. They still
operate with logical equivalence to before.

Signed-off-by: Frederick Dilger <fdilger@whamcloud.com>
Change-Id: If35b2e9db51f7296da25b798205b9f9104830bca
Reviewed-on: https://review.whamcloud.com/c/fs/lustre-release/+/55399
Tested-by: jenkins <devops@whamcloud.com>
Tested-by: Maloo <maloo@whamcloud.com>
Reviewed-by: Oleg Drokin <green@whamcloud.com>
Reviewed-by: Andreas Dilger <adilger@whamcloud.com>
Reviewed-by: Sebastien Buisson <sbuisson@ddn.com>