Solving magento#22964

It was needed to change the appendTimeIfNeeded, because isn't right to transform DateTime without hour into with hour just appending a string in the end of other string.

lib/internal/Magento/Framework/Stdlib/DateTime/Timezone.php

@@ -182,7 +182,7 @@ public function date($date = null, $locale = null, $useTimezone = true, $include
                     new \DateTimeZone($timezone)
                 );
 
-                $date = $this->appendTimeIfNeeded($date, $includeTime);
+                $date = $this->appendTimeIfNeeded($date, $includeTime, $timezone, $locale);
                 $date = $formatter->parse($date) ?: (new \DateTime($date))->getTimestamp();
                 break;
         }
@@ -347,16 +347,31 @@ public function convertConfigTimeToUtc($date, $format = 'Y-m-d H:i:s')
     }
 
     /**
-     * Retrieve date with time
-     *
      * @param string $date
-     * @param bool $includeTime
+     * @param boolean $includeTime
+     * @param string $timezone
+     * @param string $locale
      * @return string
      */
-    private function appendTimeIfNeeded($date, $includeTime)
+    private function appendTimeIfNeeded($date, $includeTime, $timezone, $locale)
     {
         if ($includeTime && !preg_match('/\d{1}:\d{2}/', $date)) {
-            $date .= " 0:00am";
+
+            $formatterWithoutHour = new \IntlDateFormatter(
+                $locale,
+                \IntlDateFormatter::SHORT,
+                \IntlDateFormatter::NONE,
+                new \DateTimeZone($timezone)
+            );
+            $convertedDate = $formatterWithoutHour->parse($date);
+            $formatterWithHour = new \IntlDateFormatter(
+                $locale,
+                \IntlDateFormatter::SHORT,
+                \IntlDateFormatter::SHORT,
+                new \DateTimeZone($timezone)
+            );
+
+            $date = $formatterWithHour->format($convertedDate);
         }
         return $date;
     }