ACP2E-1958: avoid reloading configs for each requested key; added unit tests

Author: alzota

lib/internal/Magento/Framework/Module/Test/Unit/ModuleListTest.php

@@ -129,7 +129,7 @@ public function testIsModuleInfoAvailableNoConfig(): void
     {
         $this->config
             ->method('get')
-            ->willReturnOnConsecutiveCalls(['modules' => 'testModule'], null);
+            ->willReturnOnConsecutiveCalls(null);
         $this->assertFalse($this->model->isModuleInfoAvailable());
     }
 
@@ -144,7 +144,7 @@ public function testIsModuleInfoAvailableNoConfig(): void
     private function setLoadConfigExpectation($isExpected = true): void
     {
         if ($isExpected) {
-            $this->config->expects($this->exactly(2))->method('get')->willReturn(self::$enabledFixture);
+            $this->config->expects($this->once())->method('get')->willReturn(self::$enabledFixture);
         } else {
             $this->config->expects($this->never())->method('get');
         }