Fix the meter unit types to be consistent

The unit types for certain meters generated from
pollsters are not consistent with the once generated
via notifications. This fix handles the mismatch.

DocImpact
Closes-Bug: #1460696

Change-Id: Ibd82fa4a5a4e66abaf2a6d0bbe18df4fbfac3ffb

ceilometer/network/services/fwaas.py

@@ -87,7 +87,7 @@ class FirewallPolicyPollster(base.BaseServicesPollster):
             yield sample.Sample(
                 name='network.services.firewall.policy',
                 type=sample.TYPE_GAUGE,
-                unit='policy',
+                unit='firewall_policy',
                 volume=1,
                 user_id=None,
                 project_id=fw['tenant_id'],

ceilometer/network/services/lbaas.py

@@ -186,7 +186,7 @@ class LBHealthMonitorPollster(base.BaseServicesPollster):
             yield sample.Sample(
                 name='network.services.lb.health_monitor',
                 type=sample.TYPE_GAUGE,
-                unit='monitor',
+                unit='health_monitor',
                 volume=1,
                 user_id=None,
                 project_id=probe['tenant_id'],

ceilometer/network/services/vpnaas.py

@@ -54,7 +54,7 @@ class VPNServicesPollster(base.BaseServicesPollster):
             yield sample.Sample(
                 name='network.services.vpn',
                 type=sample.TYPE_GAUGE,
-                unit='vpn',
+                unit='vpnservice',
                 volume=status,
                 user_id=None,
                 project_id=vpn['tenant_id'],
@@ -96,7 +96,7 @@ class IPSecConnectionsPollster(base.BaseServicesPollster):
             yield sample.Sample(
                 name='network.services.vpn.connections',
                 type=sample.TYPE_GAUGE,
-                unit='connection',
+                unit='ipsec_site_connection',
                 volume=1,
                 user_id=None,
                 project_id=conn['tenant_id'],