remove elasticsearch-async tests (elastic#949)

elasticsearch-async has been deprecated and its functionality brought
into elasticsearch-py proper (tests for that can be found in
async_elasticsearch_client_tests.py). Since version 3.7 of aiohttp,
the tests fail and can't easily be fixed. We plan to remove support
for this module anyway in version 6.0 of the agent, so it's an
acceptable quick fix to remove testing for the module now already.

Author: beniwohli

tests/docker-compose.yml

@@ -78,7 +78,7 @@ services:
       - pyesdata6:/usr/share/elasticsearch/data
 
   elasticsearch7:
-    image: docker.elastic.co/elasticsearch/elasticsearch:7.1.0
+    image: docker.elastic.co/elasticsearch/elasticsearch:7.9.0
     healthcheck:
       test: ["CMD", "curl", "-f", "http://localhost:9200"]
     environment:

tests/instrumentation/asyncio_tests/elasticsearch_async_client_tests.py

@@ -1,3 +1,2 @@
 elasticsearch>=6.0,<7.0
-elasticsearch-async ; python_version >= '3.7'
 -r reqs-base.txt

tests/requirements/reqs-elasticsearch-6.txt

@@ -1,4 +1,3 @@
 elasticsearch>=7.0,<8.0
-elasticsearch-async ; python_version >= '3.7'
 aiohttp ; python_version >= '3.6'
 -r reqs-base.txt