operating-systems: buer: Revert unfortunate changes

operating-systems/buer.scm

@@ -215,9 +215,8 @@
                      (list #~(build-machine
                               (name "yumiko")
                               (systems (list "x86_64-linux"))
-                              (host-key
-                               (call-with-input-file ssh-key:yumiko.pub
-                                 (@ (ice-9 textual-ports) get-string-all)))
+                              (host-key #$(plain-file-content
+                                            ssh-key:yumiko.pub))
                               (private-key "/root/.ssh/id_ed25519")
                               (user "radio")
                               (port 2222))))
@@ -260,8 +259,7 @@
           (service ntp-service-type)
           (service wpa-supplicant-service-type
                    (wpa-supplicant-configuration
-                    (config-file
-                     (local-file "/etc/wpa_supplicant.conf"))
+                    (config-file "/etc/wpa_supplicant.conf")
                     (interface "wlp2s0")
                     (extra-options `("-B"))))
           (service dhcp-client-service-type