Remove unnecessary words in Javadoc (#501)

Remove unnecessary words in Javadoc (#501)

Our Javadoc had some duplicated words, this commit fixes it.

PR: #501

src/main/java/org/junitpioneer/jupiter/ClearEnvironmentVariable.java

@@ -23,9 +23,8 @@
  * {@code @ClearEnvironmentVariable} is a JUnit Jupiter extension to clear the value
  * of a environment variable for a test execution.
  *
- * <p>The key of the environment variable to be cleared must be specified via
- * {@link #key()}. After the annotated element has been executed, After the
- * annotated method has been executed, the initial default value is restored.</p>
+ * <p>The key of the environment variable to be cleared must be specified via {@link #key()}.
+ * After the annotated element has been executed, the initial default value is restored.</p>
  *
  * <p>{@code ClearEnvironmentVariable} is repeatable and can be used on the method and
  * on the class level. If a class is annotated, the configured variable will be

src/main/java/org/junitpioneer/jupiter/ClearSystemProperty.java

@@ -23,9 +23,8 @@
  * {@code @ClearSystemProperty} is a JUnit Jupiter extension to clear the value
  * of a system property for a test execution.
  *
- * <p>The key of the system property to be cleared must be specified via
- * {@link #key()}. After the annotated element has been executed, After the
- * annotated method has been executed, the initial default value is restored.</p>
+ * <p>The key of the system property to be cleared must be specified via {@link #key()}.
+ * After the annotated element has been executed, the initial default value is restored.</p>
  *
  * <p>{@code ClearSystemProperty} is repeatable and can be used on the method and
  * on the class level. If a class is annotated, the configured property will be