printing: always use ls to find PDF, update needles

When the printing_builtin test ran on an F35 respin compose it
failed; it turns out the target filename was different for the
built-in print-to-PDF on GNOME on F35. So let's just always
use the 'ls' output to find the file, but pick the directory
to check based on whether we're using cups or not.

Also rename the needles to have unique names, and add one for
F35 GNOME.

Signed-off-by: Adam Williamson <awilliam@redhat.com>

needles/gnome/printing_use_saveas_pdf-gnome-f35-20220217.json

@@ -0,0 +1,15 @@
+{
+  "area": [
+    {
+      "ypos": 274,
+      "xpos": 206,
+      "height": 20,
+      "type": "match",
+      "width": 107
+    }
+  ],
+  "properties": [],
+  "tags": [
+    "printing_use_saveas_pdf"
+  ]
+}

tests/desktop_printing.pm

@@ -95,14 +95,10 @@ sub run {
 
     # Get the name of the printed file. The path location depends
     # on the selected method.
-    # For the built-in printing method.
-    my $filepath = "/home/test/Documents/output.pdf";
-    # If we use cups-pdf, the file will be placed elsewhere.
-    if ($usecups) {
-        my $filename = script_output("ls /home/test/Desktop/");
-        $filepath = "/home/test/Desktop/$filename";
-    }
-    
+    my $directory = $usecups ? "/home/test/Desktop" : "/home/test/Documents";
+    my $filename = script_output("ls $directory");
+    my $filepath = "$directory/$filename";
+
     # Echo that filename to the terminal for troubleshooting purposes
     diag("The file of the printed out file is located in $filepath");