Set address space limit in systemd service file

We have a bootstrap check for the maximum size of the virtual memory
address space for the Elasticsearch process. We can set this in the
service file for Elasticsearch when installed as a service on
systemd-based systems for a better user experience than them fumbling
through thinking they should set this via /etc/security/limits.d (as a
lot of pages on the Internet would tell them) not realizing that systemd
completely ignores these for services and then trying to figure out how
to add a unit file for the Elasticsearch service.

Relates #25975

distribution/src/main/packaging/systemd/elasticsearch.service

@@ -32,6 +32,9 @@ LimitNOFILE=65536
 # Specifies the maximum number of processes
 LimitNPROC=4096
 
+# Specifies the maximum size of virtual memory
+LimitAS=infinity
+
 # Specifies the maximum file size
 LimitFSIZE=infinity