Previously, pdftk (part of the ticket, badge, ... generation pipeline)
would fail with:
```
Error occurred during initialization of VM
Failed to mark memory page as executable - check if grsecurity/PaX is enabled
```
Thise caused pdf generation to fail.
Since pdftk is a java application and, according to systemd.exec(5),
> Note that [MemoryDenyWriteExecute=] is incompatible with programs and
> libraries that generate program code dynamically at runtime, including
> JIT execution engines, executable stacks, and code "trampoline" featu
> re of various C compilers.
Disabling `MemoryDenyWriteExecute=` fixes it.
