[REM] website, website_blog, website_event: remove text size on cover

addons/website/static/src/js/editor/snippets.options.js

addons/website/static/src/js/editor/wysiwyg_multizone.js

addons/website/views/snippets/snippets.xml

addons/website/views/website_templates.xml

addons/website_blog/data/website_blog_demo.xml

addons/website_blog/static/src/scss/website_blog.scss

addons/website_blog/views/website_blog_templates.xml

addons/website_event/static/src/scss/website_event.scss

addons/website_event/views/event_templates.xml