Remove \Drupal\Tests\jsonapi\Kernel\JsonapiKernelTestBase::createEntityReferenceField and just use \Drupal\Tests\field\Traits\EntityReferenceTestTrait::createEntityReferenceField

Problem/Motivation

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tl;dr
Remove \Drupal\Tests\jsonapi\Kernel\JsonapiKernelTestBase::createEntityReferenceField and use \Drupal\Tests\field\Traits\EntityReferenceTestTrait::createEntityReferenceField instead

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes

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