fix lynda.com signin

[Volkanite]

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Description of your pull request and other information

Fixes lynda.com signin. The signin page previously used by the extractor has been moved to https://www.lynda.com/signin/lynda because Lynda supports a few ways to signin and has made it clear via the previous signin page update by prompting users to first choose one of the below signin methods:

https://www.lynda.com/portal/linkedin
https://www.lynda.com/signin/lynda
https://www.lynda.com/signin/organization

closes #18158