checkpoint cbstats shows info related to vb_0 in case of invalid vbid was passed

build-1952

usage: cbstats [options]

options:
-h, --help show this help message and exit
-a iterate over all buckets (requires admin u/p)
-b BUCKETNAME the bucket to get stats from (Default: default)
-p PASSWORD the password for the bucket if one exists
Usage: cbstats host:port all
or cbstats host:port allocator
or cbstats host:port checkpoint [vbid]

example of output with wrong vbid:
[root@cen-2708 bin]# ./cbstats 10.3.121.63:11210 checkpoint vb_11
vb_0:checkpoint_extension: false
vb_0:eq_tapq:replication_ns_1@10.3.121.64:cursor_checkpoint_id: 3
vb_0:last_closed_checkpoint_id: 2
vb_0:num_checkpoint_items: 1
vb_0:num_checkpoints: 1
vb_0:num_items_for_persistence: 0
vb_0:num_open_checkpoint_items: 0
vb_0:num_tap_cursors: 1
vb_0:open_checkpoint_id: 3
vb_0:persisted_checkpoint_id: 2
vb_0:state:
active
[root@cen-2708 bin]# ./cbstats 10.3.121.63:11210 checkpoint vb_11aa
vb_0:checkpoint_extension: false
vb_0:eq_tapq:replication_ns_1@10.3.121.64:cursor_checkpoint_id: 3
vb_0:last_closed_checkpoint_id: 2
vb_0:num_checkpoint_items: 1
vb_0:num_checkpoints: 1
vb_0:num_items_for_persistence: 0
vb_0:num_open_checkpoint_items: 0
vb_0:num_tap_cursors: 1
vb_0:open_checkpoint_id: 3
vb_0:persisted_checkpoint_id: 2
vb_0:state: active

correct behavior is:

[root@cen-2708 bin]# ./cbstats 10.3.121.63:11210 checkpoint 11
vb_11:checkpoint_extension: false
vb_11:eq_tapq:replication_ns_1@10.3.121.64:cursor_checkpoint_id: 3
vb_11:last_closed_checkpoint_id: 2
vb_11:num_checkpoint_items: 1
vb_11:num_checkpoints: 1
vb_11:num_items_for_persistence: 0
vb_11:num_open_checkpoint_items: 0
vb_11:num_tap_cursors: 1
vb_11:open_checkpoint_id: 3
vb_11:persisted_checkpoint_id: 2
vb_11:state: active

better to print out message that vbid was set incorrectly