Forward port of https://github.com/elastic/elasticsearch/pull/38757
This change reverts the initial 7.0 commits and replaces them
with the 6.7 variant that still allows for the ecs flag.
This commit differs from the 6.7 variants in that ecs flag will
now default to true.
6.7: `ecs` : default `false`
7.x: `ecs` : default `true`
8.0: no option, but behaves as `true`
* Revert "Ingest node - user agent, move device to an object (#38115)"
This reverts commit 5b008a34aa.
* Revert "Add ECS schema for user-agent ingest processor (#37727) (#37984)"
This reverts commit cac6b8e06f.
* cherry-pick 5dfe1935345da3799931fd4a3ebe0b6aa9c17f57
Add ECS schema for user-agent ingest processor (#37727)
* cherry-pick ec8ddc890a34853ee8db6af66f608b0ad0cd1099
Ingest node - user agent, move device to an object (#38115) (#38121)
* cherry-pick f63cbdb9b426ba24ee4d987ca767ca05a22f2fbb (with manual merge fixes)
Dep. check for ECS changes to User Agent processor (#38362)
* make true the default for the ecs option, and update 7.0 references and tests
46bb663a09