Remove NM connectivity check file from al.org

With the ping.al.org domain added in[1] and a updated networkmanager package shipped[2], we can now remove the file from the main domain.

[1] 498d5304 ("Merge branch 'ping' into 'master'")
fabccd0f (""Move" NM connectivity check file to a subdomain")
[2] https://github.com/archlinux/svntogit-packages/commit/fb573170fc63c18f64eb4f155ed64a966a61b037

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To be merged +1 month from now.

Ref: #239 (closed), !311 (merged)