ttyrun-getty@ and serial-getty@ services conflict with each other

[sharkcz]

Cloning from a downstream bug (https://bugzilla.redhat.com/show_bug.cgi?id=1907781)

Description of problem:
Starting/Enabling ttyrun-getty@ and serial-getty@ should be mutually exclusive, since the instance cannot be shared, e.g. ttyrun-getty@hvc0 and serial-getty@hv0 cannot connect simultaneously.

I would suggest adding the following stanza to ttyrun-getty@.service unit:

-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------
[Unit]
Conflicts=serial-getty@%i.service
-------- 8< ---------------- 8< ---------------- 8< ---------------- 8< --------

How reproducible:
Always

Steps to Reproduce:

1. Start ttyrun-getty@hvc0
# systemctl start ttyrun-getty@hvc0

Actual results:
serial-getty@hvc0 fails