sdbusplus: use shorter type aliases

The sdbusplus headers provide shortened aliases for many types.
Switch to using them to provide better code clarity and shorter
lines.  Possible replacements are for:
  * bus_t
  * exception_t
  * manager_t
  * match_t
  * message_t
  * object_t
  * slot_t

Change-Id: I7948c1c8108da238952abaa3e7d400fdca80c7e5
Signed-off-by: Patrick Williams <patrick@stwcx.xyz>
diff --git a/test/test_health_metric_collection.cpp b/test/test_health_metric_collection.cpp
index 2f4b1b9..bb1512a 100644
--- a/test/test_health_metric_collection.cpp
+++ b/test/test_health_metric_collection.cpp
@@ -22,7 +22,7 @@
 {
   public:
     sdbusplus::SdBusMock sdbusMock;
-    sdbusplus::bus::bus bus = sdbusplus::get_mocked_new(&sdbusMock);
+    sdbusplus::bus_t bus = sdbusplus::get_mocked_new(&sdbusMock);
 
     static constexpr auto busName = "xyz.openbmc_project.test.HealthMon";
     static constexpr auto objPath = "/xyz/openbmc_project/sdbusplus/test";