Specify the operator option when generating term queries.

[tobio]

This restores previous functionality when querying for multi-term values in analysed fields

Fixes #6399

Summary

Restores the previous match operator behaviour when the query value is split into multiple terms after analysis.

QA

General checklist

• Added or updated **jest and [cypress]
• A changelog entry exists and is marked appropriately

[kibanamachine]

Preview documentation changes for this PR: https://eui.elastic.co/pr_6409/

[PhaedrusTheGreek]

This LGTM,

Prior to my change, we were simply concatenating terms with terms.join(' ')

   match: {
      [field]: {
        query: terms.join(' '),
        operator: andOr,
      },

When the associated field mapping was a keyword, things broke, so converting to a bool query solved that particular instance. Unfortunately I didn't take into consideration the possibility of each term also having spaces in it, which in retrospect (of course), is clear.

With this change, we have the best of both worlds. Each individual term is broken out into it's respective match query inside a bool, with the desired operator (and/or) giving us must/should, plus now we also add the appropriate operator: and/or inside each individual match, to catch cases where the individual term also contains a space (or whatever tokenization).

[cee-chen]

Fantastic, thank you for the approval and verbal walk through @PhaedrusTheGreek, and of course thank you for the contribution @tobio! I'll go ahead and approve and merge this in as Chandler is out sick this week.