build: delete arch suffix from alpine build-env image tag

deploy/docker/Dockerfile

@@ -1,4 +1,4 @@
-ARG BUILD_FROM=emqx/build-env:erl23.2.7.2-emqx-3-alpine-amd64
+ARG BUILD_FROM=emqx/build-env:erl23.2.7.2-emqx-3-alpine
 ARG RUN_FROM=alpine:3.12
 FROM ${BUILD_FROM} AS builder
 

docker.mk

@@ -64,7 +64,7 @@ docker-build:
 
 	@docker build --no-cache \
 		--build-arg PKG_VSN=$(PKG_VSN)  \
-		--build-arg BUILD_FROM=emqx/build-env:erl23.2.7.2-emqx-3-alpine-$(ARCH)  \
+		--build-arg BUILD_FROM=emqx/build-env:erl23.2.7.2-emqx-3-alpine  \
 		--build-arg RUN_FROM=$(ARCH)/alpine:3.12 \
 		--build-arg EMQX_NAME=$(EMQX_NAME) \
 		--build-arg QEMU_ARCH=$(QEMU_ARCH) \