Mark the unit tests module itself as its component

This will help to try out code coverage reporting.

Change-Id: I52953037cb1482d88102d4bf8719ec7192dfaa97
Test: presubmit
Bug: 172962242

core/java_host_unit_test_config_template.xml

@@ -17,6 +17,7 @@
 <configuration description="Runs {MODULE}">
     <option name="test-suite-tag" value="apct" />
     <option name="test-suite-tag" value="apct-unit-tests" />
+    <option name="config-descriptor:metadata" key="component" value="{MODULE}" />
 
     {EXTRA_CONFIGS}