Support APM server

[cachedout]

Summary

This PR introduces the ability to test APM server using the Beats tester.

Refs https://github.com/elastic/apm-server/issues/2733

The following tests were performed and passed:

• [x] tester-centos6-32
• [x] tester-centos6-64
• [x] tester-ubuntu1204-32
• [x] tester-debian8-64
• [x] tester-centos7-64
• [x] tester-win12-64
• [x] tester-ubuntu1604-64
• [x] tester-awslinux
• [x] tester-debian9-64
• [x] tester-sles12-64
• [x] tester-ubuntu1404-64
• [x] tester-ubuntu1804-64
• [x] tester-awslinux2
• [x] tester-centos8-64
• [x] tester-debian10-64
• [x] tester-ubuntu2004-64

The following tests were not run

• [ ] tester-win19-64 (This image does not appear to be functional)

[elasticmachine]

:green_heart: Build Succeeded

Expand to view the summary

#### Build stats * Build Cause: `[Started by user cachedout]` * Start Time: 2020-07-17T09:26:15.970+0000 * Duration: 140 min 15 sec #### Test stats :test_tube: | Test | Results | | ------------ | :-----------------------------: | | Failed | 0 | | Passed | 13204 | | Skipped | 7668 | | Total | 20872 |

[graphaelli]

thanks @cachedout!