Add a build task for cts_instant

Test: With other CLs in the topic, run 'm -j30 cts_instant'

bug: 79750671
Change-Id: Ib0381017300108a22919892070540b9e7f92aaf9
diff --git a/core/main.mk b/core/main.mk
index 033a2d9..1946edb 100644
--- a/core/main.mk
+++ b/core/main.mk
@@ -96,6 +96,8 @@
 -include tools/tradefederation/build/suites/general-tests/config.mk
 # STS-specific config.
 -include test/sts/tools/sts-tradefed/build/config.mk
+# CTS-Instant-specific config
+-include test/suite_harness/tools/cts-instant-tradefed/build/config.mk
 
 # Clean rules
 .PHONY: clean-dex-files