I18n: Message contains unescaped '100%', translation fail

[simosx]

A translatable message in WordPress contains the literal 'if you are 100% certain'. This should change to 'if you are 100%% certain'.

The gettext tools for the localisation of WordPress expect a format specifier in the translated message, thus the message is shown as untranslated on a live WordPress deployment.

The real issue is that '100% certain' is very colloquial and informal. It does not translate well in other languages/cultures.

Therefore, I suggest to fix the message,
from 'if you are 100% certain'
to the CORRECT 'if you are absolutely certain'.

Source: #: wp-admin/ms-delete-site.php:25

[ryan]

(In [13022]) Change wording in string to make translation easier. Props simosx. fixes #12173