maxStackTraceLines="0" is not honored

[nr-ahemsath]

The maxStackTraceLines configuration value (https://docs.newrelic.com/docs/agents/net-agent/configuration/net-agent-configuration/#config-maxStackTraceLines) is not honored if the value is set to "0".

Expected behavior: no stack trace lines will be sent.
Actual behavior: all available stack trace lines are sent.

Our support team brought this to our attention; a customer wants to configure the agent to keep sending error trace data to New Relic, but without any stack trace information included. Upon investigation, we found that setting maxStackTraceLines to 0 had no effect on the number of stack trace lines sent due to a flaw in the logic for handling this config value. This will be fixed in a PR shortly.