Wizard: fix datepicker reset glitch (MS-8610)

If the reset button is clicked, there is a glitch that shows error state
for a moment. This commit removes the glitch by setting the snapshot
date even for invalid values, and removes the workaround that was
previously added.

src/test/Components/CreateImageWizard/steps/Snapshot/Snapshot.test.tsx

@@ -254,6 +254,12 @@ describe('repository snapshot tab - ', () => {
     });
     // reset fills in the current date, so it should not be disabled
     await clickReset();
+    // works even for invalid values
+    await updateDatePickerWithValue('xxx');
+    await waitFor(() => {
+      expect(nextBtn).toBeDisabled();
+    });
+    await clickReset();
     await waitFor(() => {
       expect(nextBtn).toBeEnabled();
     });