craft.app.i18n.primarySiteLocale doesn't return the primary Site's locale

[mdominguez]

Description

I'm having 4 sites (nl / fr / en / de) where the 'nl' one is the primary site. view screenshot

So logically when I want to output the primary Site's locale, it should output 'nl' instead of 'de' (where 'de' is just the first Site listed, NOT the primary one)

view screenshot

Steps to reproduce

1. Create primary site first with 'nl'
2. Then create other site eg: 'de'

Additional info

• Craft version: Craft CMS 3.0.13.2
• PHP version: 7.1.16
• Database driver & version:
• Plugins & versions:

[mdominguez]

Duplicate of #3063 but here with a couple of screenshots to make it clear :)