More tests for enrich processor

[nik9000]

Adds more tests for the enrich processor around different index types.
Right now they all work fine (yay!) but this feels like a good amount of
paranoia.

[elasticsearchmachine]

Pinging @elastic/es-data-management (Team:Data Management)

[dakrone]

These are all missing a human-readable "name" for the test (the "Test that X does Y" sort of string under the initial ---), can we add those so people can see at a glance what the test is testing?

[dakrone]

LGTM, thanks for adding these Nik! I left one comment about adding a description string for the test

[nik9000]

These are all missing a human-readable "name" for the test (the "Test that X does Y" sort of string under the initial ---), can we add those so people can see at a glance what the test is testing?

I don't tend to include the words "test that" but I have pushed some more descriptive language. run was terrible.