Trim excess shellcheck annotations. Widen to all non-Korn scripts

Before, make shellcheck checked
  scripts/{commitcheck,make_gitrev,man-dates,paxcheck,zfs-helpers,zfs,
           zfs-tests,zimport,zloop}.sh
  cmd/zed/zed.d/{{all-debug,all-syslog,data-notify,generic-notify,
                 resilver_finish-start-scrub,scrub_finish-notify,
                 statechange-led,statechange-notify,trim_finish-notify,
                 zed-functions}.sh,history_event-zfs-list-cacher.sh.in}
  cmd/zpool/zpool.d/{dm-deps,iostat,lsblk,media,ses,smart,upath}
now it also checks
  contrib/dracut/{02zfsexpandknowledge/module-setup,
                  90zfs/{export-zfs,parse-zfs,zfs-needshutdown,
                         zfs-load-key,zfs-lib,module-setup,
                         mount-zfs,zfs-generator}}.sh.in
  cmd/zed/zed.d/{pool_import-led,vdev_attach-led,
                 resilver_finish-notify,vdev_clear-led}.sh
  contrib/initramfs/{zfsunlock,hooks/zfs.in,scripts/local-top/zfs}
  tests/zfs-tests/tests/perf/scripts/prefetch_io.sh
  scripts/common.sh.in
  contrib/bpftrace/zfs-trace.sh
  autogen.sh

Reviewed-by: John Kennedy <john.kennedy@delphix.com>
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Ahelenia Ziemiańska <nabijaczleweli@nabijaczleweli.xyz>
Closes #12042

contrib/dracut/90zfs/zfs-lib.sh.in

@@ -59,6 +59,7 @@ import_pool() {
 
     if ! zpool list -H "${pool}" > /dev/null 2>&1; then
         info "ZFS: Importing pool ${pool}..."
+        # shellcheck disable=SC2086
         if ! zpool import -N ${ZPOOL_IMPORT_OPTS} "${pool}" ; then
             warn "ZFS: Unable to import pool ${pool}"
             return 1
@@ -123,13 +124,12 @@ for_relevant_root_children() {
 # export_all OPTS
 #   exports all imported zfs pools.
 export_all() {
-    opts="${@}"
     ret=0
 
     IFS="${NEWLINE}"
     for pool in $(zpool list -H -o name) ; do
         if zpool list -H "${pool}" > /dev/null 2>&1; then
-            zpool export "${pool}" ${opts} || ret=$?
+            zpool export "${pool}" "$@" || ret=$?
         fi
     done
     IFS="${OLDIFS}"