Drop the useless PHP tokenizer extension install step (#1650)

It is bundled and enabled by default in the PHP language already, and adding this step raises a warning:
warning: tokenizer (tokenizer.so) is already loaded!

Also if this option disabled, it's still installed as part of the language anyway!

env-example

@@ -134,7 +134,6 @@ WORKSPACE_SSH_PORT=2222
 PHP_FPM_INSTALL_ZIP_ARCHIVE=true
 PHP_FPM_INSTALL_BCMATH=true
 PHP_FPM_INSTALL_MYSQLI=true
-PHP_FPM_INSTALL_TOKENIZER=true
 PHP_FPM_INSTALL_INTL=true
 PHP_FPM_INSTALL_IMAGEMAGICK=true
 PHP_FPM_INSTALL_OPCACHE=true