[YouTube] Fix some YoutubeStreamExtractorDefaultTest tests

- Fix typo in folder name of DescriptionTestPewdiepie test;
- Fix constant usage of DownloaderTestImpl as download implementation for
UnlistedTest and CCLicensed tests.

Author: AudricV

extractor/src/test/java/org/schabi/newpipe/extractor/services/youtube/stream/YoutubeStreamExtractorDefaultTest.java

@@ -126,7 +126,7 @@ public static class DescriptionTestPewdiepie extends DefaultStreamExtractorTest
         @BeforeAll
         public static void setUp() throws Exception {
             YoutubeTestsUtils.ensureStateless();
-            NewPipe.init(DownloaderFactory.getDownloader(RESOURCE_PATH + "pewdiwpie"));
+            NewPipe.init(DownloaderFactory.getDownloader(RESOURCE_PATH + "pewdiepie"));
             extractor = YouTube.getStreamExtractor(URL);
             extractor.fetchPage();
         }
@@ -502,7 +502,7 @@ public static class UnlistedTest {
         @BeforeAll
         public static void setUp() throws Exception {
             YoutubeTestsUtils.ensureStateless();
-            NewPipe.init(DownloaderTestImpl.getInstance());
+            NewPipe.init(DownloaderFactory.getDownloader(RESOURCE_PATH + "unlistedDefaultTest"));
             extractor = (YoutubeStreamExtractor) YouTube
                     .getStreamExtractor("https://www.youtube.com/watch?v=tjz2u2DiveM");
             extractor.fetchPage();
@@ -522,7 +522,7 @@ public static class CCLicensed {
         @BeforeAll
         public static void setUp() throws Exception {
             YoutubeTestsUtils.ensureStateless();
-            NewPipe.init(DownloaderTestImpl.getInstance());
+            NewPipe.init(DownloaderFactory.getDownloader(RESOURCE_PATH + "ccLicensed"));
             extractor = YouTube.getStreamExtractor(URL);
             extractor.fetchPage();
         }