dissect-tool: hide device column if it's a short-lived loopback device

It's pointless showing info that isn#t going to survive the current
invocation, hence hide it.

The "partition number" column is more useful since it kinda shows the
same information, but without the device node name prefixed that is
local to the currentl invocation.

src/dissect/dissect.c

@@ -961,6 +961,11 @@ static int action_dissect(DissectedImage *m, LoopDevice *d) {
         table_set_ersatz_string(t, TABLE_ERSATZ_DASH);
         (void) table_set_align_percent(t, table_get_cell(t, 0, 9), 100);
 
+        /* Hide the device path if this is a loopback device that is not relinquished, since that means the
+         * device node is not going to be useful the instant our command exits */
+        if ((!d || d->created) && (arg_json_format_flags & JSON_FORMAT_OFF))
+                table_hide_column_from_display(t, 8);
+
         for (PartitionDesignator i = 0; i < _PARTITION_DESIGNATOR_MAX; i++) {
                 DissectedPartition *p = m->partitions + i;