nixosTests.prometheus-exporters.wireguard: fix test script

A newline in the public key breaks the test script, stripping it out
fixes the test.

nixos/tests/prometheus-exporters.nix

@@ -1396,7 +1396,10 @@ let
       '';
     };
 
-    wireguard = let snakeoil = import ./wireguard/snakeoil-keys.nix; in
+    wireguard = let
+      snakeoil = import ./wireguard/snakeoil-keys.nix;
+      publicKeyWithoutNewlines = replaceStrings [ "\n" ] [ "" ] snakeoil.peer1.publicKey;
+    in
       {
         exporterConfig.enable = true;
         metricProvider = {
@@ -1418,7 +1421,7 @@ let
           wait_for_unit("prometheus-wireguard-exporter.service")
           wait_for_open_port(9586)
           wait_until_succeeds(
-              "curl -sSf http://localhost:9586/metrics | grep '${snakeoil.peer1.publicKey}'"
+              "curl -sSf http://localhost:9586/metrics | grep '${publicKeyWithoutNewlines}'"
           )
         '';
       };