Improve test and build time by using -i flag (#4758)

See #4755 for details.

libbeat/scripts/Makefile

@@ -83,10 +83,11 @@ endif
 
 
 ${BEAT_NAME}: $(GOFILES_ALL) ## @build build the beat application
-	go build
+	go build -i
 
 # Create test coverage binary
 ${BEAT_NAME}.test: $(GOFILES_ALL)
+	@go build -i -o /dev/null
 	@go test $(RACE) -c -coverpkg ${GOPACKAGES_COMMA_SEP}
 
 .PHONY: crosscompile
@@ -142,15 +143,18 @@ prepare-tests:
 .PHONY: unit-tests
 unit-tests: ## @testing Runs the unit tests with coverage.  Race is not enabled for unit tests because tests run much slower.
 unit-tests: prepare-tests
+	go test -i ${GOPACKAGES}
 	$(COVERAGE_TOOL) $(RACE) -coverprofile=${COVERAGE_DIR}/unit.cov  ${GOPACKAGES}
 
 .PHONY: unit
 unit: ## @testing Runs the unit tests without coverage reports.
+	go test -i ${GOPACKAGES}
 	go test $(RACE) ${GOPACKAGES}
 
 .PHONY: integration-tests
 integration-tests: ## @testing Run integration tests. Unit tests are run as part of the integration tests.
 integration-tests: prepare-tests
+	go test -i ${GOPACKAGES}
 	$(COVERAGE_TOOL) -tags=integration $(RACE) -coverprofile=${COVERAGE_DIR}/integration.cov  ${GOPACKAGES}
 
 #