fix(macros/LearnSidebar): update titles for consistency

[dipikabh]

Summary

This is a follow-up to the PR mdn/content#32643 (review)

Problem

1. "Core forms learning pathway" - With the updated page title "Web form building blocks" (merged change), the menu drop-down header needs to be the same. So "Core forms learning pathway" should read "Web form building blocks" (as in HTML, CSS, and JavaScript sections of the Learn sidebar).
2. "Advanced form articles" - The title needs to contain "web form" for consistency and we don't use "articles" in any of the other menus/titles.

Solution

• "Core forms learning pathway" has been updated to "Web form building blocks"
• "Advanced form articles" has been updated to "Advanced web form techniques"

Screenshots

Before	After

[dipikabh]

Thanks for reviewing and approving, @caugner!