Honor RUNTIME_JAVA_HOME for benchmarks (#28962)
Honor RUNTIME_JAVA_HOME for benchmarks (#28962)

With this commit we configure our microbenchmarks project to use the
configured RUNTIME_JAVA_HOME and to fallback on JAVA_HOME so this
behavior is consistent  with the rest of the Elasticsearch build.

Closes #28961
gfyoung/elasticsearch,s1monw/elasticsearch,coding0011/elasticsearch,GlenRSmith/elasticsearch,robin13/elasticsearch,rajanm/elasticsearch,rajanm/elasticsearch,coding0011/elasticsearch,rajanm/elasticsearch,rajanm/elasticsearch,uschindler/elasticsearch,robin13/elasticsearch,gfyoung/elasticsearch,s1monw/elasticsearch,gingerwizard/elasticsearch,GlenRSmith/elasticsearch,nknize/elasticsearch,coding0011/elasticsearch,scorpionvicky/elasticsearch,kalimatas/elasticsearch,uschindler/elasticsearch,s1monw/elasticsearch,nknize/elasticsearch,kalimatas/elasticsearch,gingerwizard/elasticsearch,gfyoung/elasticsearch,scorpionvicky/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,scorpionvicky/elasticsearch,robin13/elasticsearch,rajanm/elasticsearch,gfyoung/elasticsearch,uschindler/elasticsearch,nknize/elasticsearch,gingerwizard/elasticsearch,nknize/elasticsearch,s1monw/elasticsearch,gingerwizard/elasticsearch,uschindler/elasticsearch,uschindler/elasticsearch,HonzaKral/elasticsearch,kalimatas/elasticsearch,rajanm/elasticsearch,coding0011/elasticsearch,robin13/elasticsearch,s1monw/elasticsearch,GlenRSmith/elasticsearch,kalimatas/elasticsearch,HonzaKral/elasticsearch,robin13/elasticsearch,gfyoung/elasticsearch,HonzaKral/elasticsearch,nknize/elasticsearch,GlenRSmith/elasticsearch,kalimatas/elasticsearch,GlenRSmith/elasticsearch,gingerwizard/elasticsearch,coding0011/elasticsearch,scorpionvicky/elasticsearch,gingerwizard/elasticsearch,HonzaKral/elasticsearch