…ard failure (elastic#121720)

* Adding condition to verify if the field belongs to an index

* Update docs/changelog/121720.yaml

* Remove unnecessary comma from yaml file

* remove duplicate inference endpoint creation

* updating isMetadata to return true if mapper has the correct type

* remove unnecessary index creation in yaml tests

* Adding check if the document has returned in the yaml test

* Updating test to skip time series  check if index mode is standard

* Refactor tests to consider verifying every metafields with all index modes

* refactoring test to verify for all cases

* Adding assetFalse if not time_series and fields are from time_series

* updating test texts to have better description

(cherry picked from commit 43c841a)