IVGCVSW-2073: Move remaining backend-specific tests from armnn to backends

Change-Id: I45fd5b6dd32c435b78a54dc377a623e60978ce13
diff --git a/src/backends/reference/backend.mk b/src/backends/reference/backend.mk
index 455ab46..007efce 100644
--- a/src/backends/reference/backend.mk
+++ b/src/backends/reference/backend.mk
@@ -65,6 +65,9 @@
 
 BACKEND_TEST_SOURCES := \
         test/RefCreateWorkloadTests.cpp \
+        test/RefEndToEndTests.cpp \
+        test/RefJsonPrinterTests.cpp \
         test/RefLayerSupportTests.cpp \
         test/RefLayerTests.cpp \
+        test/RefOptimizedNetworkTests.cpp \
         test/RefRuntimeTests.cpp