use "true" for RACE_ENABLED (#15261)

Makefile

@@ -64,8 +64,9 @@ EXTRA_GOFLAGS ?=
 MAKE_VERSION := $(shell $(MAKE) -v | head -n 1)
 MAKE_EVIDENCE_DIR := .make_evidence
 
-ifneq ($(RACE_ENABLED),)
-	GOTESTFLAGS ?= -race
+ifeq ($(RACE_ENABLED),true)
+	GOFLAGS += -race
+	GOTESTFLAGS += -race
 endif
 
 STORED_VERSION_FILE := VERSION
@@ -380,7 +381,7 @@ test-check:
 .PHONY: test\#%
 test\#%:
 	@echo "Running go test with -tags '$(TEST_TAGS)'..."
-	@$(GO) test -mod=vendor -tags='$(TEST_TAGS)' -run $(subst .,/,$*) $(GO_PACKAGES)
+	@$(GO) test -mod=vendor $(GOTESTFLAGS) -tags='$(TEST_TAGS)' -run $(subst .,/,$*) $(GO_PACKAGES)
 
 .PHONY: coverage
 coverage: