Confirm that services factories work fine in Matchers

I can no longer replicate the original problems:
- Missing metadata values when matching EPerson created outside of builders (could be related to DSpace#10193)
- NPE when retrieving services from factories in class body

Author: ybnd

dspace-server-webapp/src/test/java/org/dspace/app/rest/matcher/BitstreamMatcher.java

@@ -28,7 +28,6 @@
 import org.hamcrest.Matcher;
 
 public class BitstreamMatcher {
-    // todo: this may not work in all cases!
     private static final BitstreamService bitstreamService = ContentServiceFactory.getInstance().getBitstreamService();
     private static final BundleService bundleService = ContentServiceFactory.getInstance().getBundleService();
 

dspace-server-webapp/src/test/java/org/dspace/app/rest/matcher/EPersonMatcher.java

@@ -26,7 +26,6 @@
 import org.hamcrest.Matchers;
 
 public class EPersonMatcher {
-    // todo: this may not work in all cases!
     public static final EPersonService epersonService = EPersonServiceFactory.getInstance().getEPersonService();
 
     private EPersonMatcher() { }
@@ -91,7 +90,6 @@ public static Matcher<? super Object> matchProperties(EPerson ePerson) {
                 hasJsonPath("$.type", is("eperson")),
                 hasJsonPath("$.canLogIn", not(empty())),
                 hasJsonPath("$.metadata", Matchers.allOf(
-                        // todo: this fails when matching against the eperson from AbstractIntegrationTestWithDatabase
                         MetadataMatcher.matchMetadata("eperson.firstname", epersonService.getFirstName(ePerson)),
                         MetadataMatcher.matchMetadata("eperson.lastname", epersonService.getLastName(ePerson))
                 ))

dspace-server-webapp/src/test/java/org/dspace/app/rest/matcher/ItemMatcher.java

@@ -29,7 +29,6 @@
  * @author Raf Ponsaerts (raf dot ponsaerts at atmire dot com)
  */
 public class ItemMatcher {
-    // todo: this may not work in all cases!
     private static final ItemService itemService = ContentServiceFactory.getInstance().getItemService();
 
     private ItemMatcher() { }

dspace-server-webapp/src/test/java/org/dspace/app/rest/matcher/SiteMatcher.java

@@ -18,7 +18,6 @@
 import org.hamcrest.Matcher;
 
 public class SiteMatcher {
-    // todo: this may not work in all cases!
     private static final SiteService siteService = ContentServiceFactory.getInstance().getSiteService();
 
     private SiteMatcher() { }

dspace-server-webapp/src/test/java/org/dspace/app/rest/matcher/WorkflowDefinitionMatcher.java

@@ -26,7 +26,6 @@
  * @author Maria Verdonck (Atmire) on 03/01/2020
  */
 public class WorkflowDefinitionMatcher {
-    // todo: this may not work in all cases!
     private static XmlWorkflowFactory xmlWorkflowFactory = XmlWorkflowServiceFactory.getInstance().getWorkflowFactory();
 
     private static final String WORKFLOW_DEFINITIONS_ENDPOINT