Move choose-mirror script to /usr/local/bin/

/etc/systemd/scripts/ is not a standard directory.

Run shellchek on the choose-mirror script.

.gitlab-ci.yml

@@ -13,3 +13,4 @@ lint:
         archiso/mkarchiso
         configs/{baseline,releng}/build.sh
         configs/releng/airootfs/root/.automated_script.sh
+        configs/releng/airootfs/usr/local/bin/choose-mirror

configs/releng/airootfs/etc/systemd/system/choose-mirror.service

@@ -4,7 +4,7 @@ ConditionKernelCommandLine=mirror
 
 [Service]
 Type=oneshot
-ExecStart=/etc/systemd/scripts/choose-mirror
+ExecStart=/usr/local/bin/choose-mirror
 
 [Install]
 WantedBy=multi-user.target