apm agent finds server but failed to send data (security manager)

## Describe the bug
Trying to use apm on elasticsearch jvm to get jvm metrics.
APM agent finds APM server, but fails to send any data with `java.net.SocketPermission access denied`.

## Steps to reproduce
elasticapm.properties:
```
service_name=elasticsearch
server_urls=http://apm:8200
```
dockercompose.yml:
```
elasticsearch:
image: elasticsearch:7.9.3
mem_limit: 768m
expose:
- "9200"
environment:
ES_JAVA_OPTS: -Xmx768m
HTTP_PORT: 9200
discovery.type: single-node
ELASTIC_APM_SERVER_URLS: http://apm:8200
labels:
co.elastic.logs/module: elasticsearch
app: elasticsearch
volumes:
- es-data:/usr/share/elasticsearch/data
- ./config/es/jvm.options:/usr/share/elasticsearch/config/jvm.options:ro
- ./config/es/apm:/usr/share/elasticsearch/config/apm:ro
apm:
image: store/elastic/apm-server:7.9.3
mem_limit: 64m
depends_on:
- elasticsearch
expose:
- "8200"
labels:
app: apm
environment:
apm-server.host: localhost:8200
output.elasticsearch.hosts: http://elasticsearch:9200
volumes:
- apm-data:/usr/share/apm-server/data
```

## Expected behavior
Data sent to apm server.

## Debug logs

docker logs docker_elasticsearch_1 | grep apm

```
2021-01-20 18:17:39,569 [main] INFO co.elastic.apm.agent.configuration.StartupInfo - Starting Elastic APM 1.20.0 as elasticsearch on Java 15 Runtime version: 15+36-1562 VM version: 15+36-1562 (Oracle Corporation) Linux 4.19.128-microsoft-standard
2021-01-20 18:17:39,570 [main] INFO co.elastic.apm.agent.configuration.StartupInfo - VM Arguments: [-Xshare:auto, -Des.networkaddress.cache.ttl=60, -Des.networkaddress.cache.negative.ttl=10, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -XX:+ShowCodeDetailsInExceptionMessages, -Dio.netty.noUnsafe=true, -Dio.netty.noKeySetOptimization=true, -Dio.netty.recycler.maxCapacityPerThread=0, -Dio.netty.allocator.numDirectArenas=0, -Dlog4j.shutdownHookEnabled=false, -Dlog4j2.disable.jmx=true, -Djava.locale.providers=SPI,COMPAT, -Des.networkaddress.cache.ttl=60, -Des.networkaddress.cache.negative.ttl=10, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -Dio.netty.noUnsafe=true, -Dio.netty.noKeySetOptimization=true, -Dio.netty.recycler.maxCapacityPerThread=0, -Dio.netty.allocator.numDirectArenas=0, -Dlog4j.shutdownHookEnabled=false, -Dlog4j2.disable.jmx=true, -Djava.io.tmpdir=/tmp/elasticsearch-11682935632529430251, -XX:+HeapDumpOnOutOfMemoryError, -XX:HeapDumpPath=data, -XX:ErrorFile=logs/hs_err_pid%p.log, -Xlog:gc*,gc+age=trace,safepoint:file=logs/gc.log:utctime,pid,tags:filecount=32,filesize=64m, -Djava.locale.providers=COMPAT, -javaagent:/usr/share/elasticsearch/config/apm/elastic-apm-agent.jar, -Des.cgroups.hierarchy.override=/, -Xmx768m, -XX:MaxDirectMemorySize=402653184, -Des.path.home=/usr/share/elasticsearch, -Des.path.conf=/usr/share/elasticsearch/config, -Des.distribution.flavor=default, -Des.distribution.type=docker, -Des.bundled_jdk=true]
2021-01-20 18:17:39,571 [main] WARN co.elastic.apm.agent.configuration.StartupInfo - To enable all features and decrease startup time, please configure application_packages
2021-01-20 18:17:41,275 [elastic-apm-server-healthcheck] INFO co.elastic.apm.agent.report.ApmServerHealthChecker - Elastic APM server is available: { "build_date": "2020-10-16T08:05:05Z", "build_sha": "af7b123f289d79c34c9da11471803f457eafa5c0", "version": "7.9.3"}
2021-01-20 18:17:41,301 [main] INFO co.elastic.apm.agent.impl.ElasticApmTracer - Tracer switched to RUNNING state
{"type": "server", "timestamp": "2021-01-20T18:17:43,849Z", "level": "INFO", "component": "o.e.n.Node", "cluster.name": "docker-cluster", "node.name": "daa16e1cfd08", "message": "JVM arguments [-Xshare:auto, -Des.networkaddress.cache.ttl=60, -Des.networkaddress.cache.negative.ttl=10, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -XX:+ShowCodeDetailsInExceptionMessages, -Dio.netty.noUnsafe=true, -Dio.netty.noKeySetOptimization=true, -Dio.netty.recycler.maxCapacityPerThread=0, -Dio.netty.allocator.numDirectArenas=0, -Dlog4j.shutdownHookEnabled=false, -Dlog4j2.disable.jmx=true, -Djava.locale.providers=SPI,COMPAT, -Des.networkaddress.cache.ttl=60, -Des.networkaddress.cache.negative.ttl=10, -XX:+AlwaysPreTouch, -Xss1m, -Djava.awt.headless=true, -Dfile.encoding=UTF-8, -Djna.nosys=true, -XX:-OmitStackTraceInFastThrow, -Dio.netty.noUnsafe=true, -Dio.netty.noKeySetOptimization=true, -Dio.netty.recycler.maxCapacityPerThread=0, -Dio.netty.allocator.numDirectArenas=0, -Dlog4j.shutdownHookEnabled=false, -Dlog4j2.disable.jmx=true, -Djava.io.tmpdir=/tmp/elasticsearch-11682935632529430251, -XX:+HeapDumpOnOutOfMemoryError, -XX:HeapDumpPath=data, -XX:ErrorFile=logs/hs_err_pid%p.log, -Xlog:gc*,gc+age=trace,safepoint:file=logs/gc.log:utctime,pid,tags:filecount=32,filesize=64m, -Djava.locale.providers=COMPAT, -javaagent:/usr/share/elasticsearch/config/apm/elastic-apm-agent.jar, -Des.cgroups.hierarchy.override=/, -Xmx768m, -XX:MaxDirectMemorySize=402653184, -Des.path.home=/usr/share/elasticsearch, -Des.path.conf=/usr/share/elasticsearch/config, -Des.distribution.flavor=default, -Des.distribution.type=docker, -Des.bundled_jdk=true]" }
2021-01-20 18:18:11,514 [elastic-apm-server-reporter] ERROR co.elastic.apm.agent.report.IntakeV2ReportingEventHandler - Failed to handle event of type JSON_WRITER with this error: access denied ("java.net.SocketPermission" "apm:8200" "connect,resolve")
```