JSON.DEBUG MEMORY is inaccurate

[oshadmi]

Issue #545 fixed a problem with key position on cluster,
So it does not return zeros any more,
But JSON.DEBUG MEMROY is still not returning accurate values.
For example,

127.0.0.1:6379> JSON.SET doc $ '[]'
OK
127.0.0.1:6379> JSON.DEBUG MEMORY doc $
1) (integer) 24
127.0.0.1:6379> JSON.ARRINSERT doc $ 0 '"some_string_value"'
1) (integer) 1
127.0.0.1:6379> JSON.DEBUG MEMORY doc $
1) (integer) 24
127.0.0.1:6379> JSON.STRAPPEND doc $[0] '"!"' 
1) (integer) 18
127.0.0.1:6379> JSON.DEBUG MEMORY doc $
1) (integer) 24

Should not be returning the same value both before and after ARRINSERT and JSON.STRAPPEND

[oshadmi]

Related to #559