(Optional) limit on sampleRate for statsd input plugin

[donmahallem]

Use Case

Currently when providing a high sample rate to statsd input plugin (e.g. valid:0|ms|@0.000000001 ) it causes

telegraf/plugins/inputs/statsd/statsd.go

Lines 870 to 872 in ee8dd87

	for i := 0; i < int(1.0/m.samplerate); i++ {
	field.addValue(m.floatvalue)
	}

to "hang" quite a bit. Would it be "sensible" to enforce a reasonable limit on this number with the option to modify it?

Expected behavior

Currently the main issue that this operation can take quite a bit of time. It is more of "preference" thing to fix/implement this.

Actual behavior

It runs for quite some time

Additional info