ACP2E-1512: Env variable config not working for store views with capital letters in the code

fixed disabled "use system value" issue, added unit test

Author: aplapana

app/code/Magento/Config/Test/Unit/Model/Config/Reader/Source/Deployed/SettingCheckerTest.php

@@ -69,6 +69,16 @@ protected function setUp(): void
         $this->checker = new SettingChecker($this->configMock, $placeholderFactoryMock, $this->scopeCodeResolverMock);
     }
 
+    public function testGetEnvValue(): void
+    {
+        $_ENV = array_merge($this->env, ['SOME_PLACEHOLDER' => 0, 'another_placeholder' => 1, 'some_placeholder' => 1]);
+        $this->placeholderMock->expects($this->any())
+            ->method('isApplicable')
+            ->willReturn(true);
+        $this->assertSame($this->checker->getEnvValue('SOME_PLACEHOLDER'), 1);
+        $this->assertSame($this->checker->getEnvValue('another_placeholder'), 1);
+    }
+
     /**
      * @param string $path
      * @param string $scope