Remove email subject in “Help improve this page” and improve component performance

[remibetin]

Direct link to preview: https://deploy-preview-115--wai-website-theme.netlify.app/components/teasers/

Currently, an email subject is automatically populated when clicking on email links in “Help improve this page”. See for example the “Help improve this page” section in “Accessibility Fundamentals Overview”.

To help with spam processing, this pull request:

• stops populating the email subject
• adds [include a relevant email Subject] to the email body, to encourage users to manually add an email subjet.

Resolves w3c/wai-website#941

I have applied additional improvements to the component:

• Removed the line creating a col variable: deprecated since bbade4c

• Used default filter to set a default value for feedbackmail, instead of if/else statements.

• Cached t.html and box.html includes. To make it work, I have explicitly passed the page language as argument. (See Jekyll Include Cache README)

• Introduced a plainText argument that can be passed to an t.html include. When present, <span lang="en"></span> is not added around the English text when a translation is missing. Currently, the HTML code was added to the email body...

  Example:

  <span lang="en">[include a relevant email Subject]</span>
  
  [votre commentaire ici...]
  
  J’accepte que ceci soit partagé sur une liste de diffusion archivée publiquement.
  

Test

I built the site before and after the edits: no unexpected changes.

Impact on Render Stats (using --profile flag)

Before caching t.html and box.html includes:

Filename	Count	Bytes	Time
jekyll-remote-theme-20241105-81016-1uqh35/_includes/t.html	12667	534.87K	0.652
jekyll-remote-theme-20241105-81016-1uqh35/_includes/box.html	5272	726.19K	0.167
jekyll-remote-theme-20241105-81016-1uqh35/_includes/feedback-box.html	1106	1470.27K	1.105

After caching t.html and box.html includes:

Filename	Count	Bytes	Time
jekyll-remote-theme-20241105-82502-d57quu/_includes/t.html	5754	231.31K	0.383
jekyll-remote-theme-20241105-82502-d57quu/_includes/box.html	3075	331.72K	0.078
jekyll-remote-theme-20241105-82502-d57quu/_includes/feedback-box.html	1106	1431.32K	0.492

[netlify]

✅ Deploy Preview for wai-website-theme ready!

Name	Link
🔨 Latest commit	73433a0
🔍 Latest deploy log	https://app.netlify.com/sites/wai-website-theme/deploys/6729faaa3c0b440008b3e1b8
😎 Deploy Preview	https://deploy-preview-115--wai-website-theme.netlify.app
📱 Preview on mobile	Toggle QR Code... Use your smartphone camera to open QR code link.

---

To edit notification comments on pull requests, go to your Netlify site configuration.

[shawna-slh]

thanks!