using runtime-jdk=bundled prior to elasticsearch 7 results in elasticserach using java from the path

[hub-cap]

Running esrally with --runtime-jdk=bundled on a version prior to 7.0.0, does not error out. Instead it just uses java it finds on the PATH, and also does not honor environment variables or the car JDK definitions

➜  env|grep JAVA
JAVA10_HOME=/opt/java/jdk-10.0.1
JAVA11_HOME=/opt/java/jdk-11
JAVA12_HOME=/opt/java/jdk-12
JAVA13_HOME=/opt/java/jdk-13.0.1
JAVA7_HOME=/opt/java/jdk1.7.0_80
JAVA8_HOME=/opt/java/jdk1.8.0_172
JAVA9_HOME=/opt/java/jdk-9.0.4
JAVA_HOME=/opt/java/jdk-14.0.1
JAVA14_HOME=/opt/java/jdk-14.0.1
➜  . .venv/bin/activate                                                                                            
(.venv) ➜  esrally --distribution-version=6.8.0 --runtime-jdk=bundled  

and in another tab

➜  ~ ps aux|grep java

baz      26174  264  1.9 4969716 1281528 ?     Sl   16:12   0:18 /bin/java -Xms1g -Xmx1g -XX:+UseConcMarkSweepGC -XX:CMSInitiatingOccupancyFraction=75 -XX:+UseCMSInitiatingOccupancyOnly -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 -Dlog4j.shutdownHookEnabled=false -Dlog4j2.disable.jmx=true -Djava.io.tmpdir=/tmp/elasticsearch-9416369777544052768 -XX:+HeapDumpOnOutOfMemoryError -XX:HeapDumpPath=/home/baz/.rally/benchmarks/races/c8c3e160-9af4-40be-bfdc-80e9d89d85e8/rally-node-0/heapdump -XX:ErrorFile=/home/baz/.rally/benchmarks/races/c8c3e160-9af4-40be-bfdc-80e9d89d85e8/rally-node-0/logs/server/hs_err_pid%p.log -Djava.locale.providers=COMPAT -XX:UseAVX=2 -XX:+ExitOnOutOfMemoryError -Des.path.home=/home/baz/.rally/benchmarks/races/c8c3e160-9af4-40be-bfdc-80e9d89d85e8/rally-node-0/install/elasticsearch-6.8.0 -Des.path.conf=/home/baz/.rally/benchmarks/races/c8c3e160-9af4-40be-bfdc-80e9d89d85e8/rally-node-0/install/elasticsearch-6.8.0/config -Des.distribution.flavor=oss -Des.distribution.type=tar -cp /home/baz/.rally/benchmarks/races/c8c3e160-9af4-40be-bfdc-80e9d89d85e8/rally-node-0/install/elasticsearch-6.8.0/lib/* org.elasticsearch.bootstrap.Elasticsearch -d -p pid          

[danielmitterdorfer]

I think this should be a fairly targeted fix. We already define a car variable runtime.jdk.bundled (in rally-teams) to determine whether a bundled JDK is allowed and it can be used to detect this condition.

However when we resolve JAVA_HOME we don't check anymore whether a bundled JDK is allowed:

rally/esrally/mechanic/java_resolver.py

Lines 41 to 44 in b422323

	if runtime_jdk_versions[0] == "bundled":
	logger.info("Using JDK bundled with Elasticsearch.")
	# assume that the bundled JDK is the highest available; the path is irrelevant
	return allowed_runtime_jdks[0], None