Remove redundant "go build -mod=vendor" from docker build

Change-Id: I2d488376c637fa8ac96b49fb6bae6ec25811c84a
diff --git a/VERSION b/VERSION
index ee90284..74bcb8d 100644
--- a/VERSION
+++ b/VERSION
@@ -1 +1 @@
-1.0.4
+1.0.5-dev
diff --git a/docker/Dockerfile b/docker/Dockerfile
index 96d3c5b..a1b04ad 100644
--- a/docker/Dockerfile
+++ b/docker/Dockerfile
@@ -27,7 +27,7 @@
 # Build openolt
 SHELL ["/bin/ash", "-o", "pipefail", "-c"]
 ENV GO111MODULE=on
-RUN  go mod vendor && go build -mod=vendor && go build -mod=vendor -o /go/bin/openolt-scale-tester
+RUN  go mod vendor && go build -mod=vendor -o /go/bin/openolt-scale-tester
 
 # -------------
 # Image creation stage