Get rid of _param:influxdb_user

The StackLight username for InfluxDB is set to 'lma' by default. If one
wants to override it, it should be done in the user model.
diff --git a/heka/remote_collector/cluster.yml b/heka/remote_collector/cluster.yml
index a18c111..c757ff9 100644
--- a/heka/remote_collector/cluster.yml
+++ b/heka/remote_collector/cluster.yml
@@ -7,7 +7,7 @@
       influxdb_host: ${_param:heka_influxdb_host}
       influxdb_port: ${_param:influxdb_port}
       influxdb_database: ${_param:influxdb_database}
-      influxdb_username: ${_param:influxdb_user}
+      influxdb_username: lma
       influxdb_password: ${_param:influxdb_stacklight_password}
       aggregator_host: ${_param:heka_aggregator_host}
       aggregator_port: ${_param:aggregator_port}
diff --git a/heka/remote_collector/single.yml b/heka/remote_collector/single.yml
index 4b38afb..916308f 100644
--- a/heka/remote_collector/single.yml
+++ b/heka/remote_collector/single.yml
@@ -7,7 +7,7 @@
       influxdb_host: ${_param:heka_influxdb_host}
       influxdb_port: ${_param:influxdb_port}
       influxdb_database: ${_param:influxdb_database}
-      influxdb_username: ${_param:influxdb_user}
+      influxdb_username: lma
       influxdb_password: ${_param:influxdb_stacklight_password}
       aggregator_host: ${_param:heka_aggregator_host}
       aggregator_port: ${_param:aggregator_port}