Dockerfile update to use Go as builder (#12006)

* Removal of ko, image-autobumper

* Pull build action

* fix typo

* more typos

* test of dockerfile on PR

cmd/image-autobumper/Dockerfile

@@ -1,13 +1,27 @@
-FROM europe-docker.pkg.dev/kyma-project/prod/testimages/alpine-git:v20240924-6fb36f45
+FROM golang:1.23-alpine as builder
 
 WORKDIR /app
 
 COPY go.mod go.sum ./
 
+# Download all dependencies. Dependencies will be cached if the go.mod and go.sum files are not changed
 RUN go mod download
 
+# Copy the source to the Working Directory inside the container
 COPY . .
 
-RUN CGO_ENABLED=0 GOOS=linux GOARCH=amd64 go build -o image-autobumper ./cmd/image-autobumper
+WORKDIR /app/cmd/image-autobumper
 
-ENTRYPOINT ["./image-autobumper"]
+# Build the Go app with static linking
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -o main .
+
+FROM alpine:3.20.3
+
+LABEL io.kyma-project.source=github.com/kyma-project/test-infra/cmd/image-autobumper
+
+# Copy the built Go app from the builder stage
+COPY --from=builder /app/cmd/image-autobumper/main /image-autobumper
+
+RUN apk add --no-cache ca-certificates git && \
+    chmod +x /image-autobumper
+ENTRYPOINT ["/image-autobumper"]