Revert^2 "[metrics] Add StatsdBackend"

Adds a new backend that allows reporting ART's metrics to statsd, where
they can then be uploaded to Westworld.

Manual Testing Instructions:

Run the following commands.

    m statsd_testdrive
    adb shell setprop dalvik.vm.extra-opts              \
                      -Xwrite-metrics-to-statsd\\\      \
                      -Xwrite-metrics-to-log\\\         \
                      -Xmetrics-reporting-period=10
    adb shell stop && adb shell start
    statsd_testdrive 332

After about a minute, you should see several atoms logged from ART.

This reverts commit dbad1ef673140c66cdbcbbf40424674ae8e2b4c8.
Reason for revert: Added statsd apex to prebuilts

Bug: 178236337
Test: Manual, see above
Test: see instructions on https://r.android.com/1591932
Change-Id: I2071983c04c51efe88df6a56c59fc418fe6e9424
12 files changed