Clarify pre-aggregation build error messages

[joshhubers]

Describe the bug
I've started testing out ROLLUP_ONLY mode for a staging environment and a handful of my queries get a Error: No pre-aggregation exists for that query. And some get "Error: Your configuration restricts query requests to only be served from pre-aggregations, and no pre-aggregation was found matching this query. Either update your pre-aggregations or disable rollup only mode in your Cube.js configuration.".

@igorlukanin replied to me in this slack thread: https://cube-js.slack.com/archives/CC0403RRR/p1632169055242600

Stating that the difference between the two is:

• No pre-aggregation exists for that query should mean "No pre-aggregation table has been built for this query yet"
• No pre-aggregation was found matching that query... means your query does not match an existing pre-aggregate.

I see that the second message is relatively new, and isn't a terrible output, but when combined with the vagueness of the first it gets confusing.

@igorlukanin's recommendation for the first message would be something like: No pre-aggregation table has been built for this query yet.

I tend to agree with this suggestion, but maybe would also offer an action item to tell the developer this is expected and no action is required such as:

No pre-aggregation table has been built for this query yet. Please wait while the worker populates your aggregate

Version:
0.28.38

Additional context
Probably a good first issue. If you give me the thumbs up on the message I would be happy to fork and open an MR.

[paveltiunov]

@joshhubers Hey Josh! Thanks for the feedback! It's helpful. cc @keydunov