Remove duplicate code in .travis.yml

The "$TRAVIS_PHP_VERSION != '7.0'" condition was duplicated

See #5580.

.travis.yml

@@ -14,7 +14,7 @@ env:
 
 before_script:
   - if [[ $TRAVIS_PHP_VERSION = '7.0' && $DB = 'sqlite' ]]; then PHPUNIT_FLAGS="--coverage-clover ./build/logs/clover.xml"; else PHPUNIT_FLAGS=""; fi
-  - if [[ $TRAVIS_PHP_VERSION != '7.0' && $TRAVIS_PHP_VERSION != 'hhvm' && $TRAVIS_PHP_VERSION != '7.0' ]]; then phpenv config-rm xdebug.ini; fi
+  - if [[ $TRAVIS_PHP_VERSION != '7.0' && $TRAVIS_PHP_VERSION != 'hhvm' ]]; then phpenv config-rm xdebug.ini; fi
   - composer self-update
   - composer install --prefer-source
 
@@ -77,4 +77,4 @@ sudo: false
 
 cache:
   directories:
-    - $HOME/.composer/cache
+    - $HOME/.composer/cache