Dockerfile: Remove redundant build step

According to the comment, this step pre-populates the cache. However,
the actual build step also populates the cache, so any additional work
done by this step is redundant.

Author: mdbooth

Dockerfile

@@ -34,11 +34,6 @@ RUN --mount=type=cache,target=/go/pkg/mod \
 # Copy the sources
 COPY ./ ./
 
-# Cache the go build into the the Go’s compiler cache folder so we take benefits of compiler caching across docker build calls
-RUN --mount=type=cache,target=/root/.cache/go-build \
-    --mount=type=cache,target=/go/pkg/mod \
-    go build .
-
 # Build
 ARG package=.
 ARG ARCH