Use try/multi-catch for some reflection-related exceptions

There are more places in the code that could benefit from this but
these are particularly egregious and easy to spot.

Change-Id: Iccef1e03e6c36bb83bf6dc1397f54817dd05af33

gerrit-launcher/src/main/java/com/google/gerrit/launcher/GerritLauncher.java

@@ -156,10 +156,7 @@ public final class GerritLauncher {
     final Method main;
     try {
       main = clazz.getMethod("main", argv.getClass());
-    } catch (SecurityException e) {
-      System.err.println("fatal: unknown command " + name);
-      return 1;
-    } catch (NoSuchMethodException e) {
+    } catch (SecurityException | NoSuchMethodException e) {
       System.err.println("fatal: unknown command " + name);
       return 1;
     }