build: Fix clean-up of vendor (argoproj#4363)

Signed-off-by: Alex Collins <[email protected]>

Makefile

@@ -1,9 +1,6 @@
 export SHELL:=/bin/bash
 export SHELLOPTS:=$(if $(SHELLOPTS),$(SHELLOPTS):)pipefail:errexit
 
-# This means we only one shell, and therefore you can use `trap` to clean-up
-.ONESHELL:
-
 # https://stackoverflow.com/questions/4122831/disable-make-builtin-rules-and-variables-from-inside-the-make-file
 MAKEFLAGS += --no-builtin-rules
 .SUFFIXES:
@@ -112,15 +109,13 @@ PROTO_BINARIES := $(GOPATH)/bin/protoc-gen-gogo $(GOPATH)/bin/protoc-gen-gogofas
 
 # go_install,path
 define go_install
- trap 'rm -Rf vendor' EXIT
  [ -e vendor ] || go mod vendor
  go install -mod=vendor ./vendor/$(1)
 endef
 
 # protoc,my.proto
 define protoc
  # protoc $(1)
- trap 'rm -Rf vendor' EXIT
  [ -e vendor ] || go mod vendor
  protoc \
  -I /usr/local/include \
@@ -274,6 +269,7 @@ codegen: \
  $(GOPATH)/bin/mockery
  # `go generate ./...` takes around 10s, so we only run on specific packages.
  go generate ./persist/sqldb ./pkg/apiclient/workflow ./server/auth ./server/auth/sso ./workflow/executor
+ rm -Rf vendor
 
 $(GOPATH)/bin/mockery:
  ./hack/recurl.sh dist/mockery.tar.gz https://github.com/vektra/mockery/releases/download/v1.1.1/mockery_1.1.1_$(shell uname -s)_$(shell uname -m).tar.gz
@@ -311,7 +307,6 @@ $(GOPATH)/bin/goimports:
  go get golang.org/x/tools/cmd/[email protected]
 
 pkg/apis/workflow/v1alpha1/generated.proto: $(GOPATH)/bin/go-to-protobuf $(PROTO_BINARIES) $(TYPES)
- trap 'rm -Rf vendor' EXIT
  [ -e vendor ] || go mod vendor
  ${GOPATH}/bin/go-to-protobuf \
  --go-header-file=./hack/custom-boilerplate.go.txt \