Drop implicit code coverage

Because not all PHP installs have code coverage enabled, and that makes
testing more difficult, and slower than necessary. Instead, use local config
if you need to always have code coverage.

phpunit.xml.dist

@@ -20,9 +20,4 @@
             </exclude>
         </whitelist>
     </filter>
-    <logging>
-        <log type="coverage-html" target="./build/coverage" />
-        <log type="coverage-clover" target="./build/logs/clover.xml" />
-        <log type="junit" target="./build/logs/logfile.xml"/>
-    </logging>
 </phpunit>