Limit the number of golangci-lint jobs to one

If you want the old behaviour back, use:
e.g. make lint GOLINT_JOBS=`nproc`

Running multiple linters takes a lot of RAM.
And it only saves us like 15 seconds anyway ?

Makefile

@@ -47,6 +47,8 @@ KERNEL_VERSION ?= 4.16.14
 
 GO_VERSION ?= $(shell go version | cut -d' ' -f3 | sed -e 's/go//')
 GOLINT_VERSION ?= v1.17.1
+# Limit number of default jobs, to avoid the CI builds running out of memory
+GOLINT_JOBS ?= 1
 export GO111MODULE := on
 
 GOOS ?= $(shell go env GOOS)
@@ -276,6 +278,7 @@ out/linters/golangci-lint:
 .PHONY: lint
 lint: pkg/minikube/assets/assets.go pkg/minikube/translate/translations.go out/linters/golangci-lint
 	./out/linters/golangci-lint run \
+	  --concurrency ${GOLINT_JOBS} \
 	  --deadline 4m \
 	  --build-tags "${MINIKUBE_INTEGRATION_BUILD_TAGS}" \
 	  --enable goimports,gocritic,golint,gocyclo,interfacer,misspell,nakedret,stylecheck,unconvert,unparam \