Remove memlock suggestion from systemd service

The systemd service file that ships with Elasticsearch installs on
systemd-based systems contains a suggestion for setting LimitMEMLOCK if
the user wants to enable bootstrap.memory_lock. However, this setting
this in the installed service file goes against best practices for
working with systemd, and goes against our existing documentation for
how to set this. Therefore, we should not have this suggestion in the
service file otherwise users might be led to think they should edit it
there.

Relates #25979

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

@@ -35,11 +35,6 @@ LimitNPROC=4096
 # Specifies the maximum file size
 LimitFSIZE=infinity
 
-# Specifies the maximum number of bytes of memory that may be locked into RAM
-# Set to "infinity" if you use the 'bootstrap.memory_lock: true' option
-# in elasticsearch.yml and 'MAX_LOCKED_MEMORY=unlimited' in ${path.env}
-#LimitMEMLOCK=infinity
-
 # Disable timeout logic and wait until process is stopped
 TimeoutStopSec=0