Implement timeout for collector config test

[bernd]

Problem description

The collector config test command ("Parameters for Configuration Validation") needs to be executed with a timeout so it cannot block forever.

I ran into this when testing the new disk spool (beta) feature of the newer filebeat versions. Testing the filebeat configuration with a configured disk spool seems to be locking the disk spool directory/file. This is a problem when there is an existing filebeat instance running that is using the same disk spool config. The test command blocked indefinitely.

I consider this a bug in the filebeat implementation but the sidecar needs a timeout for the test command to avoid blocking the collector test. Something like this can happen with other collector backends as well.

Steps to reproduce the problem

1. Configure a filebeat backend with a disk spool
2. Let the sidecar start the filebeat backend
3. Edit and save the filebeat configuration in graylog
4. Watch the sidecar executing the test command for the filebeat ➡️ it never finishes

Environment

• Sidecar Version: 1.0.0-alpha.1 (rev d92f8e5)
• Graylog Version: 3.0.0-alpha.2-SNAPSHOT (rev 20ab7325e)