Migrate/restore Kibana's config

Kibana was updated in early 2020, and the existing config is no longer read.

20:09 <+olasd> (had to change the configured config index from .kibana-6 to .kibana-7)
20:16 <+olasd> (looks like the config is therefore blank, which is... annoying)
20:17 <+olasd> (i'll stop poking at it now, please make a task to migrate/restore the old config?)

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Migrated from T2534 (view on Phabricator)