Fix x86_64 arch typo in systemsmanagement:Agama:Devel.xml file

[okynos]

We have detected a problem in mentioned XML file that lead to some jobs not launched.
This PR solves that.

[Martchus]

It looks like you have to update unit tests as well, though:

+++ obs/systemsmanagement:Agama:Devel/base//print_openqa.after  2024-09-06 13:55:06.324472504 +0000
@@ -1,5 +1,5 @@
 /usr/bin/openqa-cli api -X post isos?async=1 \
- ARCH=86_64 \
+ ARCH=x86_64 \
  ASSET_256=agama-installer.x86_64-9.0.0-openSUSE-Build17.9.iso.sha256 \
  BUILD=17.9 \

[okynos]

Fixed! Thanks for your advice