correct span_limit_per_segment default value (#3261)
correct span_limit_per_segment default value (#3261)

change `agent.span_limit_per_segment` default value to match the default value of `SPAN_LIMIT_PER_SEGMENT` in https://github.com/apache/skywalking/blob/master/apm-sniffer/apm-agent-core/src/main/java/org/apache/skywalking/apm/agent/core/conf/Config.java
ascrutae/sky-walking,ascrutae/sky-walking,OpenSkywalking/skywalking,apache/skywalking,OpenSkywalking/skywalking,apache/skywalking,apache/skywalking,ascrutae/sky-walking,apache/skywalking,apache/skywalking,apache/skywalking,ascrutae/sky-walking,apache/skywalking