Fix smoke tests for apm-server

[simitt]

Smoke tests are currently failing with these issues:

8.8 OS smoke tests:

Error: importing EC2 Key Pair (provisioner_key): InvalidKeyPair.Duplicate: The keypair already exists
	status code: 400, request id: 54f2e2b3-388c-4195-b3f0-c772a930dbbe

8.9 OS smoke tests:

-> Asserting logs-apm.error-* contains expected documents documents...
Didn't find 1 indexed documents error.id=9876543210abcdeffedcba0123456789, total hits 0
{"took":0,"timed_out":false,"_shards":{"total":0,"successful":0,"skipped":0,"failed":0},"hits":{"total":{"value":0,"relation":"eq"},"max_score":0.0,"hits":[]}}

ESS basic-upgrade-for-latest:

-> Sending events to APM Server...
{"ok":false,"message":"The instance rejected the connection."}

ESS legacy-standalone-major-managed-for 7.17

-> Sending events to APM Server...
{"ok":false,"message":"The instance rejected the connection."}

[kruskall]

8.8 OS smoke tests:

I've backported #11285 to 8.8. This is so that we can use #10829 correctly.

8.9 OS smoke tests:

I'm still investigating

ESS basic-upgrade-for-latest:

I think this is not an issue with APM Server. I rerun the tests and they passed

ESS legacy-standalone-major-managed-for 7.17

Same as above

[kruskall]

Ok, I think both 8.8 and 8.9 should be fixed.

8.9 is failing because there is no 8.9.1-SNAPSHOT available on cloud yet.

As for the 7.17 smoke tests:

I think these are just flaky tests, there's no error on our end. Restarting them seems to fix it.

[simitt]

Great! Thanks for the fixes.