fdo#57950: Remove last chained appends from avmedia

Change-Id: I0906bf7493828c5923f3243c6849a2eca5f37bb0
Signed-off-by: Marcos Paulo de Souza <marcos.souza.org@gmail.com>
Reviewed-on: https://gerrit.libreoffice.org/1548Reviewed-by: Miklos Vajna <vmiklos@suse.cz>
Tested-by: Miklos Vajna <vmiklos@suse.cz>

avmedia/source/framework/mediaitem.cxx

@@ -470,11 +470,7 @@ bool EmbedMedia(uno::Reference<frame::XModel> const& xModel,
             xTransaction->commit();
         }
 
-        OUStringBuffer buf("vnd.sun.star.Package:");
-        buf.append(media);
-        buf.append(sal_Unicode('/'));
-        buf.append(filename);
-        o_rEmbeddedURL = buf.makeStringAndClear();
+        o_rEmbeddedURL = "vnd.sun.star.Package:" + media + "/" + filename;
         return true;
     }
     catch (uno::Exception const&)