Remove travis `group: legacy` and use their latest infrastructure (#10094)

* Removed group:legacy from travis.yml template

* use latest php 5.3 instead of php 5.3.3

* Run MySQL off the RAM in our CI server to have fast builds

.travis.yml

 # do not edit this file manually, instead run the generate:travis-yml console command
-# if you are a Piwik core developer, edit this template file to auto generate the .travis.yml: https://github.com/piwik/piwik/blob/master/plugins/TestRunner/templates/travis.yml.twig
+# if you are a Piwik core developer, to auto generate the .travis.yml:
+#   1) edit this template file: https://github.com/piwik/travis-scripts/blob/master/generator/templates/travis.yml.twig
+#   2) commit the updated submodule in `piwik/tests/travis/`
 
 # when modifying this file, please consider whether your changes should apply to plugin .travis.yml files. if not, check whether the pluginName twig var is empty,
 # otherwise your changes will be synced with every plugin that uses an auto generated .travis.yml
@@ -9,11 +11,9 @@
 
 language: php
 
-group: legacy
-
 php:
   - 5.6
-  - 5.3.3
+  - 5.3
 #  - hhvm
 
 services:
@@ -60,15 +60,15 @@ matrix:
     - php: 7
   exclude:
     # Run test suites separately only on PHP 5.6 with PDO
-    - php: 5.3.3
+    - php: 5.3
       env: TEST_SUITE=SystemTests MYSQL_ADAPTER=PDO_MYSQL
-    - php: 5.3.3
+    - php: 5.3
       env: TEST_SUITE=IntegrationTests MYSQL_ADAPTER=PDO_MYSQL
-    - php: 5.3.3
+    - php: 5.3
       env: TEST_SUITE=AllTests MYSQL_ADAPTER=PDO_MYSQL
     - php: 7
       env: TEST_SUITE=AllTests MYSQL_ADAPTER=PDO_MYSQL
-    - php: 5.3.3
+    - php: 5.3
       env: TEST_SUITE=UnitTests MYSQL_ADAPTER=PDO_MYSQL
     - php: hhvm
       env: TEST_SUITE=SystemTests MYSQL_ADAPTER=PDO_MYSQL
@@ -76,7 +76,7 @@ matrix:
       env: TEST_SUITE=IntegrationTests MYSQL_ADAPTER=PDO_MYSQL
     - php: hhvm
       env: TEST_SUITE=UnitTests MYSQL_ADAPTER=PDO_MYSQL
-    # run UI tests on PHP 5.3.3 only
+    # run UI tests on PHP 5.3 only
     - php: 5.6
       env: TEST_SUITE=UITests MYSQL_ADAPTER=PDO_MYSQL UITEST_EXTRA_OPTIONS="--run-first-half-only"
     - php: 5.6
@@ -84,21 +84,21 @@ matrix:
     # run all tests not on PHP 5.6 and run MySQLI tests only on 5.6
     - php: 5.6
       env: TEST_SUITE=AllTests MYSQL_ADAPTER=PDO_MYSQL
-    - php: 5.3.3
+    - php: 5.3
       env: TEST_SUITE=AllTests MYSQL_ADAPTER=MYSQLI
     - php: 7
       env: TEST_SUITE=AllTests MYSQL_ADAPTER=MYSQLI
     - php: hhvm
       env: TEST_SUITE=AllTests MYSQL_ADAPTER=MYSQLI
     # Javascript tests need to run only on one PHP version
-    - php: 5.3.3
+    - php: 5.3
       env: TEST_SUITE=JavascriptTests MYSQL_ADAPTER=PDO_MYSQL
     - php: hhvm
       env: TEST_SUITE=JavascriptTests MYSQL_ADAPTER=PDO_MYSQL
     - php: 7
       env: TEST_SUITE=JavascriptTests MYSQL_ADAPTER=PDO_MYSQL
     # AngularJS tests need to run only on one PHP version
-    - php: 5.3.3
+    - php: 5.3
       env: TEST_SUITE=AngularJSTests MYSQL_ADAPTER=PDO_MYSQL SKIP_COMPOSER_INSTALL=1
     - php: hhvm
       env: TEST_SUITE=AngularJSTests MYSQL_ADAPTER=PDO_MYSQL SKIP_COMPOSER_INSTALL=1
@@ -136,13 +136,21 @@ before_script:
   # disable opcache to avoid random failures on travis
   - echo "opcache.enable=0" >> ~/.phpenv/versions/$(phpenv version-name)/etc/php.ini
 
+  # make tmpfs and run MySQL on it for reasonnable performance
+  - sudo mkdir /mnt/ramdisk
+  - sudo mount -t tmpfs -o size=1024m tmpfs /mnt/ramdisk
+  - sudo stop mysql
+  - sudo mv /var/lib/mysql /mnt/ramdisk
+  - sudo ln -s /mnt/ramdisk/mysql /var/lib/mysql
+  - sudo start mysql
+
   # print out mysql information
   - mysql --version
   - mysql -e "SELECT VERSION();"
 
   # configure mysql
   - mysql -e "SET GLOBAL sql_mode = 'NO_ENGINE_SUBSTITUTION,STRICT_TRANS_TABLES'" # Travis default
-  # try to avoid mysql has gone away errors
+  # try to avoid 'mysql has gone away' errors
   - mysql -e "SET GLOBAL wait_timeout = 36000;"
   - mysql -e "SET GLOBAL max_allowed_packet = 134209536;"
   - mysql -e "SHOW VARIABLES LIKE 'max_allowed_packet';"

expected-ui-screenshots @ d9c8bed4

-Subproject commit 73cbd0026c6bda598cf0f72b286a7e6a38c3652a
+Subproject commit d9c8bed45a274a1dd5eedc596df69aff11888da8

travis @ 4deb817b

-Subproject commit 2551892dc296f1abc500acf7b04380689a64588b
+Subproject commit 4deb817b1a9707754514be0620bb44fb7b979683