[BP:MB-36198]Query: Advise function confusing message

Build 6.5.0-4380

Steps to reproduce:

1. Load standard `beer-sample` bucket.
2. Runt the following query 

select count from `beer-sample`

this will be executed successfully.

Now run this:

advise select count from `beer-sample`

and response will be this:

[

{

"#operator": "Advise",

"advice": {

"#operator": "IndexAdvice",

"adviseinfo": [

{| |"recommended_indexes": "No index recommendation at this time: no keyspace found."| |}

]

},

"query": "select count from `beer-sample`"

}

]

Here is the question: which keyspace is not found?

Same actions for build 6.5.0-4349 give this advise response:

[

{

"#operator": "Advise",

"advice": {

"#operator": "IndexAdvice",

"adviseinfo": [

{| |"recommended_indexes": "No index recommendation at this time."| |}

]

},

"query": "select count from `beer-sample`"

}

]