Update Rally config file template

With this commit we update the Rally config file template so it does not
include any JDK references. With elastic/rally#518 we will resolve JDK
versions using the `JAVAx_HOME` environment variables.

Relates elastic/rally#518
Closes elastic#70
Relates elastic#71

night_rally/fixtures/ansible/roles/rally-update/templates/rally.ini.j2

@@ -1,5 +1,5 @@
 [meta]
-config.version = 16
+config.version = 17
 
 [node]
 root.dir = /var/lib/jenkins/.rally/benchmarks
@@ -12,10 +12,6 @@ env.name = {{rally_environment}}
 remote.repo.url = https://github.com/elastic/elasticsearch.git
 elasticsearch.src.subdir = elasticsearch
 
-[runtime]
-java.home = /var/lib/jenkins/.java/java8
-java10.home = /var/lib/jenkins/.java/openjdk10
-
 [benchmarks]
 local.dataset.cache = ${node:root.dir}/data