fix: Remove hreflang from Impressum/Mentions légales

Step 1: What is changing in this MR?

Some pages like mentions-legales and Impressum had the English hreflang tag in the HTML of the page despite having only one language available for the page.

Here are some different scenarios to test if everything is okay after the refactor:

Review app for Mentions Legales
Review app for Impressum
Review app for Home
Review app for two longer URL page

Dev Note:

We had to change some logic inside the meta.ts file in order to fix this problem, since the code was getting too big with many if statments I refactored the code to make it shorter and more simple, so in the same block of code it will work for all the 3 cases:

• pages with only one language (that is not english)
• homepage
• pages with longer URL, two level path

Closes #2891 (closed)