Move fpm listen for easier config override

[yosifkit]

#1564 (comment):

We need to make sure daemonize = no is as late as possible, but listen = 9000 could be higher

This should make it easier to override the listen directive. I don't think this is breaking, but there is still probably someone relying on listen being later rather than earlier (like if they delete/replace the whole docker.conf). So, this can wait until after the new year. Or maybe I can gate this to only apply to the next release of each PHP version.

Fixes #1564

[tianon]

This being in zz-docker.conf is a little bit load-bearing unless we want to modify files shipped with/by PHP itself: 😅

$ docker run --rm --pull=always php:fpm grep -rn '^listen' /usr/local/etc/php-fpm.d
fpm: Pulling from library/php
Digest: sha256:baa4dd163e5c9e95c4ba31773173b408c69c824f6a21da56af274a47e7ddbee6
Status: Image is up to date for php:fpm
/usr/local/etc/php-fpm.d/www.conf.default:41:listen = 127.0.0.1:9000
/usr/local/etc/php-fpm.d/www.conf:41:listen = 127.0.0.1:9000
/usr/local/etc/php-fpm.d/zz-docker.conf:5:listen = 9000