decouple API coverage report from main test suite target

... so that we can conditionally include the report only on
select branches of the build services configs

Bug: 77975055
Test: make -j cts dist                # no reports generated
      make -j cts-api-coverage dist   # reports generated

Change-Id: Iee812134f607e1e0580462e93dbc39268336bf4d
diff --git a/CtsCoverage.mk b/CtsCoverage.mk
index b3c66f5..8a0eef8 100644
--- a/CtsCoverage.mk
+++ b/CtsCoverage.mk
@@ -94,11 +94,14 @@
 .PHONY: cts-combined-xml-coverage
 cts-combined-xml-coverage : $(cts-combined-xml-coverage-report)
 
-# Put the test coverage report in the dist dir if "cts" is among the build goals.
-$(call dist-for-goals, cts, $(cts-test-coverage-report):cts-test-coverage-report.html)
-$(call dist-for-goals, cts, $(cts-verifier-coverage-report):cts-verifier-coverage-report.html)
-$(call dist-for-goals, cts, $(cts-combined-coverage-report):cts-combined-coverage-report.html)
-$(call dist-for-goals, cts, $(cts-combined-xml-coverage-report):cts-combined-coverage-report.xml)
+.PHONY: cts-api-coverage
+cts-coverage-report-all: cts-test-coverage cts-verifier-coverage cts-combined-coverage cts-combined-xml-coverage
+
+# Put the test coverage report in the dist dir if "cts-api-coverage" is among the build goals.
+$(call dist-for-goals, cts-api-coverage, $(cts-test-coverage-report):cts-test-coverage-report.html)
+$(call dist-for-goals, cts-api-coverage, $(cts-verifier-coverage-report):cts-verifier-coverage-report.html)
+$(call dist-for-goals, cts-api-coverage, $(cts-combined-coverage-report):cts-combined-coverage-report.html)
+$(call dist-for-goals, cts-api-coverage, $(cts-combined-xml-coverage-report):cts-combined-coverage-report.xml)
 
 # Arguments;
 #  1 - Name of the report printed out on the screen