JVM heap dump path

By default, Elasticsearch configures the JVM to dump the heap on out of memory exceptions to the default data directory (this is /var/lib/elasticsearch for the RPM and Debian package distributions, and the data directory under the root of the Elasticsearch installation for the tar and zip archive distributions). If this path is not suitable for receiving heap dumps, you should modify the entry -XX:HeapDumpPath=... in jvm.options. If you specify a directory, the JVM will generate a filename for the heap dump based on the PID of the running instance. If you specify a fixed filename instead of a directory, the file must not exist when the JVM needs to perform a heap dump on an out of memory exception, otherwise the heap dump will fail.