You could use Heavy Forwarder or build a App for Splunk Cloud to filter your Logs. If you know, how your unnecessary Logs look like, you can filter it:
add in props.conf
TRANSFORMS-asa_filter_cloud = filterAsaLogs
add in transforms.conf
[filterAsaLogs]
SOURCE_KEY = _raw
DEST_KEY = queue
FORMAT = nullQueue
REGEX = (your regex to detect them)
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