handling of metrics with : colon in them seems broken

I'm just finishing up migrating from carbon to graphouse/clickhouse and found that we have a bunch of snmp metrics that failed to backfill/load. I can work around this by using numeric MIBs but thought that I should add an issue here to help others in case they don't have that workaround.

Something like the following will work on graphite/carbon but fails to ingest into clickhouse/graphouse.

``` 2023
root@admin02:~# echo "test.bash.st-a::ts 42 `date +%s`" | nc localhost 2023
root@admin02:~# echo "test.bash.st-a::ts 42 `date +%s`" | nc localhost 2023
root@admin02:~# echo "test.bash.st-a::ts 42 `date +%s`" | nc localhost 2023 ```