Tweak the writing style of the problem reporting text
with the following changes:
- Use an en dash to separate the "learn more" link
- Use a period at the end of the phrase
When the privacy policy link from the distro isn't
available when calling G_OS_INFO_KEY_PRIVACY_POLICY_URL,
"gnome.org/privacy-policy" is used instead. However,
GNOME doesn't have any infrastructure for automatic
problem reporting; also, that link doesn't even mention
about problem reporting, so it's completely unrelated.
Fix by removing not setting any link if
G_OS_INFO_KEY_PRIVACY_POLICY_URL doesn't return any URL.
Closes https://gitlab.gnome.org/GNOME/gnome-control-center/-/issues/2926
