Fix use of hostname in Windows service (#34193)

To pass the HOSTNAME envrionment variable to the Windows service, we
have to add some command line flags to the service invocation. Namely,
we have to specify that we are passing HOSTNAME variable, and we will
pass for it the value of %%COMPUTERNAME%%. This ensures that if the
hostname is changed, we pick this up the next time that the service is
started. This change is needed for the service now that we use the
HOSTNAME as the default node name.

distribution/src/bin/elasticsearch-service.bat

@@ -173,7 +173,7 @@ if not "%SERVICE_USERNAME%" == "" (
 	)
 )
 
-"%EXECUTABLE%" //IS//%SERVICE_ID% --Startup %ES_START_TYPE% --StopTimeout %ES_STOP_TIMEOUT% --StartClass org.elasticsearch.bootstrap.Elasticsearch --StartMethod main ++StartParams --quiet --StopClass org.elasticsearch.bootstrap.Elasticsearch --StopMethod close --Classpath "%ES_CLASSPATH%" --JvmMs %JVM_MS% --JvmMx %JVM_MX% --JvmSs %JVM_SS% --JvmOptions %ES_JAVA_OPTS% ++JvmOptions %ES_PARAMS% %LOG_OPTS% --PidFile "%SERVICE_ID%.pid" --DisplayName "%SERVICE_DISPLAY_NAME%" --Description "%SERVICE_DESCRIPTION%" --Jvm "%%JAVA_HOME%%%JVM_DLL%" --StartMode jvm --StopMode jvm --StartPath "%ES_HOME%" %SERVICE_PARAMS%
+"%EXECUTABLE%" //IS//%SERVICE_ID% --Startup %ES_START_TYPE% --StopTimeout %ES_STOP_TIMEOUT% --StartClass org.elasticsearch.bootstrap.Elasticsearch --StartMethod main ++StartParams --quiet --StopClass org.elasticsearch.bootstrap.Elasticsearch --StopMethod close --Classpath "%ES_CLASSPATH%" --JvmMs %JVM_MS% --JvmMx %JVM_MX% --JvmSs %JVM_SS% --JvmOptions %ES_JAVA_OPTS% ++JvmOptions %ES_PARAMS% %LOG_OPTS% --PidFile "%SERVICE_ID%.pid" --DisplayName "%SERVICE_DISPLAY_NAME%" --Description "%SERVICE_DESCRIPTION%" --Jvm "%%JAVA_HOME%%%JVM_DLL%" --StartMode jvm --StopMode jvm --StartPath "%ES_HOME%" %SERVICE_PARAMS% ++Environment HOSTNAME="%%COMPUTERNAME%%"
 
 if not errorlevel 1 goto installed
 echo Failed installing '%SERVICE_ID%' service