Remove DNS event reporting level

Reporting level was used only by microbenchmarks, but CI go/apct-net
doesn't show a significant timing difference between test runs with and
without reporting enabled.

Test: atest resolv_integration_test
Test: m netd_benchmark && adb sync data && adb shell /data/benchmarktest64/netd_benchmark/netd_benchmark
Change-Id: I0db0522e1cf229649c2516973d8942549ccd5476