test: Don't generate a Nix conf in the makefile

The config is overriden by the test_init perl function, so it’s at best misleading to create a first one there

Created by  regnat  on April 28, 2021
3J4Y5K4QSAO4MHONWCKX4VKV2HWWXB2VKD7XPWIKQYKMAN4WENPQC
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