Q:

How to disable core dumps on Debian 8

I pretend I've already tried everything out there, but my Debian 8 keeps creating core dumps when something crashes. It's happening about once or twice in a month. It's a production server for a few websites, with packaged Apache 2.4, php5-fpm and mysql. I suspect it's php5-fpm crashing because I get the dump file in the DocumentRoot folder. The file I get is named "core" and it is somewhere in the order of gigabytes in size.
Here is what I've already done to disable core dumps, without success:
ln -s /dev/null /etc/systemd/coredump.conf

and then rebooted. No dice.
echo '*               hard    core    0' >> /etc/security/limits.conf
echo "fs.suid_dumpable = 0" >> /etc/sysctl.conf
sysctl -p

and then rebooted. Still no dice. I've NOT set kernel.suid_dumpable to 0, because I found it later but when I found it I also read that zero is its default. These settings should not make any difference anyway, because php5-fpm is not setuid. The same goes for Apache and mysql, just in case it's not php5-fpm crashing.
For the time being there is a script that looks for core dumps and deletes them. Crontab does the rest, but it is not the best solution.
How do I globally and unconditionally disable core dumps in Debian 8?

A:

After Michael Hampton's comment to the Froggiz' answer, I noticed that Debian seems to lack a coredump.conf manpage, so I've looked for it on the internet and found it. That manpage contains a lot of useful informations and I wonder why Debian ships without it (maybe Debian is shipping without the whole systemd-coredump thing?). 
However from that manpage and the systemd-coredump manpage it seems that the core files I get do not come from systemd, because systemd puts them in /var/lib/systemd/coredump or in the journal depending on the Storage option, but never in the working directory of the crashed process. Moreover the systemd-coredump manpage (also missing in Debian) says that for the core dump functionality to work, you need to configure the kernel.core_pattern sysctl parameter to make the kernel actually hand the core dump to systemd-coredump.
I've then looked at Debian value for kernel.core_pattern: Debian comes with that parameter set to "core" by default, which happens to be exactly the name of the core dump files I get.
I now suppose that setting 
kernel.core_pattern=|/bin/true

(or /bin/false for that matter) in sysctl.conf as per the core(5) manpage will solve the problem.
I'm going to evetually accept my answer in a few weeks if I notice the server stops creating core files. I'm sorry I can't accept Michael's comment as answer, but many thanks to him for pointing me in what I believe is the right direction.
EDIT: I've found here a way to test the configuration without having to wait for a spontaneous crash and I confirm this is the correct answer.

