TIKA-4838 - align the test comment with the sample-entry wording

Author: dschmidt

tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-audiovideo-module/src/test/java/org/apache/tika/parser/mp4/MP4ParserTest.java

@@ -366,7 +366,7 @@ private Set<String> getVals(Metadata m, String k) {
     @Test
     public void testDrmProtectedM4a() throws Exception {
         //the sample description declares a protected 'drms' sample entry: the
-        //format is the protection scheme and has-drm is set
+        //format is the protected sample entry format and has-drm is set
         Metadata metadata = new Metadata();
         getText("testMP4_drm.m4a", metadata);
         assertEquals("true", metadata.get(Audio.HAS_DRM));