remove lib-url-check() function from lib docs LESS

[gelanivishal]

Original Pull Request

#19412

was removed as this function does not exist anymore

Description (*)

lib-url-check was removed from lib/web/source before and also later from docs. As it was not removed from docs less files it now breaks "grunt exec" command as this function does not exist nowhere.

connected PR:
#17479 - removes it from Docs
#11371 - removes from source Less

Fixed Issues (if relevant)

Manual testing scenarios (*)

Grunt exec will not fail after change

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)

[magento-engcom-team]

Hi @gelanivishal. Thank you for your contribution
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[magento-engcom-team]

Hi @sivaschenko, thank you for the review.
ENGCOM-3696 has been created to process this Pull Request

[orlangur]

@sivaschenko such cleanup is not needed in 2.2 according to Magento Code Contributions Guide

[sivaschenko]

@orlangur this is not a cleanup, this is a fix for grunt exec

[sivaschenko]

@gelanivishal thanks for the port, however, the issue with grunt exec cannot be reproduced on 2.2 so this pull request should not be merged to 2.2. Closing. Do not hesitate to contact me if you think that's incorrect