Drop screenshot app from GNOME app start/stop tests

It was removed from the default install:
https://pagure.io/fedora-comps/c/5371509
in favor of a new screenshot mechanism that's built in to GNOME
Shell.

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

needles/gnome/apps/apps_menu_screenshot-20200316.json

@@ -1,15 +0,0 @@
-{
-  "properties": [],
-  "tags": [
-    "apps_menu_screenshot"
-  ],
-  "area": [
-    {
-      "xpos": 203,
-      "ypos": 582,
-      "width": 51,
-      "height": 32,
-      "type": "match"
-    }
-  ]
-}

needles/gnome/apps/apps_run_screenshot-20200618.json

@@ -1,15 +0,0 @@
-{
-  "area": [
-    {
-      "ypos": 54,
-      "type": "match",
-      "xpos": 123,
-      "height": 21,
-      "width": 115
-    }
-  ],
-  "properties": [],
-  "tags": [
-    "apps_run_screenshot"
-  ]
-}

tests/apps_startstop/gnome/screenshot.pm

@@ -1,28 +0,0 @@
-use base "installedtest";
-use strict;
-use testapi;
-use utils;
-
-# This test checks that Screenshot starts.
-
-sub run {
-    my $self = shift;
-    
-    # Start the application
-    start_with_launcher('apps_menu_screenshot', 'apps_menu_utilities');
-    # Check that is started
-    assert_screen 'apps_run_screenshot';
-    # Register application
-    register_application("gnome-screenshot");
-    # Close the application
-    quit_with_shortcut();
-    
-}
-
-sub test_flags {
-    return {always_rollback => 1};
-}
-
-1;
-
-# vim: set sw=4 et: