[statsd/tools] allow multiple connected devices

// Multiple devices connected
Test: adb devices
List of devices attached
02211FQC200065	device
98141FFBA005QD	device
Test: out/host/linux-x86/bin/statsd_testdrive -s 98141FFBA005QD 261
Test: out/host/linux-x86/bin/statsd_localdrive -s 98141FFBA005QD get-data 261

// Single device connected
Test: adb devices
98141FFBA005QD	device
Test: out/host/linux-x86/bin/statsd_testdrive 261
Test: out/host/linux-x86/bin/statsd_localdrive get-data 261

BUG: 152913040
Change-Id: I54009b9151565ddb5512a4f7b3ff8ef67c3a2055