[MNG-8605] The log file should be appended to (#2137)

Author: gnodet

impl/maven-logging/src/main/java/org/apache/maven/slf4j/SimpleLoggerConfiguration.java

@@ -231,7 +231,7 @@ private static OutputChoice computeOutputChoice(String logFile, boolean cacheOut
             return new OutputChoice(cacheOutputStream ? OutputChoiceType.CACHED_SYS_OUT : OutputChoiceType.SYS_OUT);
         } else {
             try {
-                FileOutputStream fos = new FileOutputStream(logFile);
+                FileOutputStream fos = new FileOutputStream(logFile, true);
                 PrintStream printStream = new PrintStream(fos);
                 return new OutputChoice(printStream);
             } catch (FileNotFoundException e) {