datadog: ignore google health checks in datadog logs

[mattkrick]

don't push the HC to datadog

for example: https://app.datadoghq.com/apm/traces?query=env%3Astaging%20service%3Aweb&agg_m=count&agg_m_source=base&agg_t=count&cols=core_service%2Ccore_resource_name%2Clog_duration%2Clog_http.method%2Clog_http.status_code&fromUser=false&graphType=flamegraph&historicalData=true&messageDisplay=inline&panel_tab=flamegraph&query_translation_version=v0&shouldShowLegend=true&sort=time&sort_by=time&sort_order=asc&spanID=2697719920649396865&spanType=all&storage=hot&timeHint=1743704764572&trace=AwAAAZX85zCc_oqMVAAAABhBWlg4NTBUdkFBQzc5U085azdrNGhuQWwAAAAkMDE5NWZkM2QtMGIzMi00YjE5LWJiNjctMjYzMWU0ZTU0NmI2AAp7YQ&traceID=67eed2bc00000000257039f985cd6281&view=spans&start=1743704760031&end=1743791160031&paused=false