[Backport] DOBISSUE date format changed after customer tries to register with sa…

[viral-wagento]

Original Pull Request

#15272

Description

When DOB is enabled on the registration page and existing customer tries to re-registration page, DOB format was changed. See the screenshot.

Manual testing scenarios

1. Tested in my local environment and fixed issue.

Contribution checklist

• Pull request has a meaningful description of its purpose
• All commits are accompanied by meaningful commit messages
• All new or changed code is covered with unit/integration tests (if applicable)
• All automated tests passed successfully (all builds on Travis CI are green)

[sidolov]

@viral-wagento , original pull request has a different solution, please, update current PR with latest fixes from the original.

[sidolov]

Hi @viral-wagento , this PR does not fix the problem described in issue.

Steps to reproduce:

1. Set Show Date of Birth=Optional
2. Try to create the customer with an email that belongs to other registered customers.
3. Fiil Date of Birth field.
4. Click Create an Account.

Result:
Incorrect format of date in Date of Birth field

[sidolov]

@viral-wagento , I am closing this PR now due to inactivity.
Please reopen and update if you wish to continue.
Thank you for the collaboration!