Fix deprecations

Problem/Motivation

When running tests in Drupal 9.2.0 there are a number of deprecation warnings:

  10x: Relying on entity queries to check access by default is deprecated in drupal:9.2.0 and an error will be thrown from drupal:10.0.0. Call \Drupal\Core\Entity\Query\QueryInterface::accessCheck() with TRUE or FALSE to specify whether access should be checked. See https://www.drupal.org/node/3201242
    5x in MetricsEndpointTest::testMetrics from Drupal\Tests\prometheus_exporter\Kernel
    5x in MetricsEndpointTest::testDisabledMetrics from Drupal\Tests\prometheus_exporter\Kernel

  3x: Installing the tables key_value and key_value_expire with the method KernelTestBase::installSchema() is deprecated in drupal:9.1.0 and is removed from drupal:10.0.0. The tables are now lazy loaded and therefore will be installed automatically when used. See https://www.drupal.org/node/3143286
    1x in PrometheusExporterSettingsTest::testSettingsForm from Drupal\Tests\prometheus_exporter\Kernel\Form
    1x in MetricsEndpointTest::testMetrics from Drupal\Tests\prometheus_exporter\Kernel
    1x in MetricsEndpointTest::testDisabledMetrics from Drupal\Tests\prometheus_exporter\Kernel

Steps to reproduce

Run tests against Drupal 9.2.0

Proposed resolution

Fix deprecations

Remaining tasks

Review patch

User interface changes

N/A

API changes

N/A

Data model changes

N/A