Runner hostname can contain an underscore, which breaks mpi jobs

Overview

When running an mpi job inside the CI once in a while one gets something like this:

While trying to create a regular expression of the node names
 used in this application, the regex parser has detected the
 presence of an illegal character in the following node name:
   node:  runner-vBzMytn_-project-10573529-concurrent-0
 Node names must be composed of a combination of ascii letters,
 digits, dots, and the hyphen ('-') character. See the following
 for an explanation:
   https://en.wikipedia.org/wiki/Hostname
 Please correct the error and try again.

Please make the hostnames standard conform.

Workaround

Register a new Runner to get a different token which hopefully doesn't have _ inside of it.