Fix some Checkstyle issues

- Remove unused imports
- Fix issues relating to line length / whitespace
- Update Checkstyle suppression in matcher classes with new check name

src/test/java/fr/xephi/authme/AuthMeMatchers.java

@@ -11,7 +11,8 @@ import java.util.Objects;
 /**
  * Custom matchers for AuthMe entities.
  */
-@SuppressWarnings("checkstyle:JavadocMethod") // Justification: Javadoc would be huge because of the many parameters
+// Justification: Javadoc would be huge because of the many parameters
+@SuppressWarnings("checkstyle:MissingJavadocMethod")
 public final class AuthMeMatchers {
 
     private AuthMeMatchers() {

src/test/java/fr/xephi/authme/data/limbo/LimboPlayerMatchers.java

@@ -17,7 +17,8 @@ import static org.hamcrest.collection.IsIterableContainingInOrder.contains;
 /**
  * Contains matchers for LimboPlayer.
  */
-@SuppressWarnings("checkstyle:JavadocMethod") // Justification: Javadoc would be huge because of the many parameters
+// Justification: Javadoc would be huge because of the many parameters
+@SuppressWarnings("checkstyle:MissingJavadocMethod")
 public final class LimboPlayerMatchers {
 
     private LimboPlayerMatchers() {