Revert "small fix and add tests"

This reverts commit fa0259c.

Author: GoodDayForSurf

packages/devextreme/js/__internal/core/localization/date.global_formats.test.ts

@@ -26,8 +26,7 @@ const saveAndRestore = (): { save: () => void; restore: () => void } => {
           // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
           delete currentConfig[key];
         } else {
-          // eslint-disable-next-line @typescript-eslint/no-explicit-any
-          (currentConfig as any)[key] = savedValues[key];
+          currentConfig[key] = savedValues[key];
         }
       });
     },
@@ -188,10 +187,7 @@ describe('date localization - dateTimeFormatPresets', () => {
         },
       });
 
-      const customFormatter = (value: number | Date): string => {
-        const d = value instanceof Date ? value : new Date(value);
-        return `custom:${d.getFullYear()}`;
-      };
+      const customFormatter = (d: Date): string => `custom:${d.getFullYear()}`;
       const result = dateLocalization.format(new Date(2020, 0, 2), { formatter: customFormatter });
 
       expect(result).toBe('custom:2020');

packages/devextreme/js/__internal/core/m_config.test.ts

@@ -83,12 +83,6 @@ const configMethod = (...args) => {
   });
 
   extend(config, newConfig);
-  const formatKeys = ['dateFormat', 'timeFormat', 'dateTimeFormat', 'numberFormat', 'dateTimeFormatPresets'] as const;
-  for (const key of formatKeys) {
-    if (key in newConfig && newConfig[key] === undefined) {
-      config[key] = undefined;
-    }
-  }
 };
 
 // @ts-expect-error typescript cant see global

packages/devextreme/js/__internal/core/m_config.ts

@@ -27,8 +27,7 @@ describe('m_global_format_config', () => {
         // eslint-disable-next-line @typescript-eslint/no-dynamic-delete
         delete currentConfig[key];
       } else {
-        // eslint-disable-next-line @typescript-eslint/no-explicit-any
-        (currentConfig as any)[key] = savedValues[key];
+        currentConfig[key] = savedValues[key];
       }
     });
   });