Merge forwardport of magento/magento2#11351 to 2.3-develop branch

Applied pull request patch https://github.com/magento/magento2/pull/11351.patch (created by @manuelson) based on commit(s):
  1. d01bc6b
  2. 0296657

Fixed GitHub Issues in 2.3-develop branch:
  - magento/magento2#11332: How to Fix the wrong input format of Customer date of birth (reported by @selusi)

Author: magento-engcom-team

app/code/Magento/Customer/Block/Widget/Dob.php

@@ -228,7 +228,7 @@ public function getHtmlExtraParams()
      */
     public function getDateFormat()
     {
-        return $this->_localeDate->getDateFormat(\IntlDateFormatter::SHORT);
+        return $this->_localeDate->getDateFormatWithLongYear();
     }
 
     /**

app/code/Magento/Customer/Test/Unit/Block/Widget/DobTest.php

@@ -31,7 +31,7 @@ class DobTest extends \PHPUnit\Framework\TestCase
     const YEAR = '2014';
 
     // Value of date('Y', strtotime(self::DATE))
-    const DATE_FORMAT = 'M/d/yy';
+    const DATE_FORMAT = 'M/d/Y';
 
     /** Constants used by Dob::setDateInput($code, $html) */
     const DAY_HTML =