Reduce code smells (#2089)

Reduce code smells found by deepsource.io. We focused on the low-hanging fruits and not breaking any api.

scm-webapp/src/test/java/sonia/scm/api/InvalidFormatExceptionMapperTest.java

@@ -65,10 +65,10 @@ class InvalidFormatExceptionMapperTest {
   }
 
   static class ObjectWithEnum {
-    public Enum e;
+    public TestEnum e;
   }
 
-  enum Enum {
+  enum TestEnum {
     ONE, TWO
   }
 }

scm-webapp/src/test/java/sonia/scm/repository/DefaultRepositoryManagerPerfTest.java

@@ -162,7 +162,7 @@ public class DefaultRepositoryManagerPerfTest {
 private long calculateAverage(List<Long> times) {
   Long sum = 0L;
   if(!times.isEmpty()) {
-    for (Long time : times) {
+    for (long time : times) {
         sum += time;
     }
     return Math.round(sum.doubleValue() / times.size());