Remove errorCollector.ignoreErrors config

[vuqtran88]

Consider the following:

• Removes the errorCollector.ignoreErrors config code usages in the agent.
• Updates the default shipped newrelic.config with the replaced config.
  changing from:

	<errorCollector enabled="true">
		<ignoreErrors>
			<exception>System.IO.FileNotFoundException</exception>
			<exception>System.Threading.ThreadAbortException</exception>
		</ignoreErrors>

to

	<errorCollector enabled="true">
		< ignoreClasses >
			< errorClass >System.IO.FileNotFoundException</errorClass >
			< errorClass >System.Threading.ThreadAbortException</errorClass >
		</ignoreClasses >

• Logs out "This {oldConfiguration} is obsoleted. Please use this {newConfiguration}." message when these configs are used in the agent v9.0. This will help Support with troubleshooting.
• Updates related integration tests.

Notes:
We don't want to remove these deprecated configs from the xml schema because it will cause configuration parsing exception when upgrade which will crash the agent.

Acceptance Criterion:

• Integration tests pass.
• Make sure SSC for ignored/expected error still works. SSC should override local config.
• Expect warning log messages when old configs are used.