MDL-72407 videojs: Remove videojs-flash and videojs-swf libraries

Apart from removing these libraries because the Flash Player was deprecated
in 2017 and officially discontinued on 31 December 2020, the rtmp and useflash
settings have been removed too (they make no sense anymore).

filter/mediaplugin/tests/filter_test.php

@@ -36,7 +36,6 @@ function test_filter_mediaplugin_link() {
 
         // We need to enable the media plugins.
         \core\plugininfo\media::set_enabled_plugins('vimeo,youtube,videojs,html5video,html5audio');
-        set_config('useflash', true, 'media_videojs');
 
         $filterplugin = new filter_mediaplugin(null, array());
 
@@ -59,7 +58,6 @@ function test_filter_mediaplugin_link() {
             '<a href="http://youtu.be/JghQgA2HMX8" class="href=css">test file</a>',
             '<a href="http://y2u.be/JghQgA2HMX8" class="href=css">test file</a>',
             '<a class="youtube" href="http://www.youtube.com/watch?v=JghQgA2HMX8">test file</a>',
-            '<a class="_blanktarget" href="http://moodle.org/testfile/test.flv?d=100x100">test flv</a>',
             '<a class="hrefcss" href="http://www.youtube.com/watch?v=JghQgA2HMX8">test file</a>',
             '<a  class="content"     href="http://moodle.org/testfile/test.ogg">test ogg</a>',
             '<a     id="audio"      href="http://moodle.org/testfile/test.mp3">test mp3</a>',

media/player/videojs/amd/src/loader.js

@@ -24,7 +24,6 @@
  */
 
 import Ajax from 'core/ajax';
-import Config from 'core/config';
 import {eventTypes} from 'core_filters/events';
 import LocalStorage from 'core/localstorage';
 import Notification from 'core/notification';
@@ -88,14 +87,10 @@ const notifyVideoJS = e => {
                 // Add YouTube to the list of modules we require.
                 modulePromises.push(import('media_videojs/Youtube-lazy'));
             }
-            if (config.techOrder && config.techOrder.indexOf('flash') !== -1) {
-                // Add Flash to the list of modules we require.
-                modulePromises.push(import('media_videojs/videojs-flash-lazy'));
-            }
+
             Promise.all([langStrings, ...modulePromises])
             .then(([langJson, videojs]) => {
                 if (firstLoad) {
-                    videojs.options.flash.swf = `${Config.wwwroot}/media/player/videojs/videojs/video-js.swf`;
                     videojs.options.playbackRates = [0.5, 0.75, 1, 1.25, 1.5, 1.75, 2];
                     videojs.options.userActions = {
                         hotkeys: true,