Make remote config quiet until endpoint is discovered

[smola]

What Does This Do

Make remote config quiet until endpoint is discovered

Also make some more initialization lazy.

Motivation

Remote config poller has a lower polling interval than feature discovery. In the previous version, remote config polling every 5 seconds got too verbose until a remote config endpoint was discovered (which would never happened if the agent simply had no remote config enabled).

Additional Notes

Example of log before this PR:

web_1    | [dd.trace 2022-10-21 11:18:21:216 +0000] [dd-remote-config] DEBUG datadog.remoteconfig.ConfigurationPoller - Failed to poll remote configuration from (no endpoint discovered yet)
web_1    | java.io.IOException: Endpoint has not been discovered yet
web_1    | 	at datadog.remoteconfig.ConfigurationPoller.fetchConfiguration(ConfigurationPoller.java:201)
web_1    | 	at datadog.remoteconfig.ConfigurationPoller.sendRequest(ConfigurationPoller.java:212)
web_1    | 	at datadog.remoteconfig.ConfigurationPoller.poll(ConfigurationPoller.java:179)
web_1    | 	at datadog.trace.util.AgentTaskScheduler$PeriodicTask.run(AgentTaskScheduler.java:299)
web_1    | 	at datadog.trace.util.AgentTaskScheduler$Worker.run(AgentTaskScheduler.java:254)
web_1    | 	at java.base/java.lang.Thread.run(Thread.java:829)