If you have the Windows Infrastructure app installed on this SH, it requires knowledge objects from the AD and DNS apps so these need to be installed to make those messages go away.
The alternative is to disable the eventtypes (which if you are not using AD or DNS should not have any impact on the Windows Infrastructure functionality)
Create a /splunk_app_windows_infrastructure/local/eventtypes.conf file with the following to disable the unneeded eventtypes. This should suppress those messages
[msad-anomalous-events]
disabled=1
[msad-dirsvcs-anomalous-events]
disabled=1
[msad-rep-errors]
disabled=1
[msad-dns-events]
disabled=1
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