Disabling Mageia 7 chroots in Copr

[Pavel Raiskup]

I have just disabled Mageia 7 chroots in Copr.

According to the Mageia support page [1], Mageia 7 reached the end of its life
on May.

This effectively means that from this moment, it is no longer possible to submit
builds for the following chroots:

- mageia-7-x86_64
- mageia-7-i586
- mageia-7-aarch64

The existing build results for F32 chroots will be automatically removed after
180 days, but feel free to individually prolong your Copr chroots.

[1] https://www.mageia.org/en/support/

Pavel