Remove duplicate empty lines in generated Dockerfiles

Checked with:

```Shell
find . -type f -print0 | xargs -0 pcregrep -M '\n\n\n'
```

docker/Dockerfile.j2

@@ -37,7 +37,6 @@ RUN apk add --no-cache --upgrade \
     curl \
     tar
 {% else %}
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8
@@ -76,14 +75,16 @@ FROM {{ build_stage_base_image }} as build
 {% if "sqlite" in target_file %}
 # set sqlite as default for DB ARG for backward compatibility
 ARG DB=sqlite
+
 {% elif "mysql" in target_file %}
 # set mysql backend
 ARG DB=mysql
+
 {% elif "postgresql" in target_file %}
 # set postgresql backend
 ARG DB=postgresql
-{% endif %}
 
+{% endif %}
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8
@@ -244,8 +245,8 @@ ENV SSL_CERT_DIR=/etc/ssl/certs
 
 {% if "amd64" not in target_file %}
 RUN [ "cross-build-start" ]
-{% endif %}
 
+{% endif %}
 # Install needed libraries
 {% if "alpine" in runtime_stage_base_image %}
 RUN apk add --no-cache \

docker/aarch64/mysql/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8

docker/aarch64/sqlite/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8

docker/amd64/mysql/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8
@@ -88,7 +87,6 @@ ENV ROCKET_ENV "staging"
 ENV ROCKET_PORT=80
 ENV ROCKET_WORKERS=10
 
-
 # Install needed libraries
 RUN apt-get update && apt-get install -y \
     --no-install-recommends \

docker/amd64/mysql/Dockerfile.alpine

@@ -82,7 +82,6 @@ ENV ROCKET_PORT=80
 ENV ROCKET_WORKERS=10
 ENV SSL_CERT_DIR=/etc/ssl/certs
 
-
 # Install needed libraries
 RUN apk add --no-cache \
         openssl \

docker/amd64/postgresql/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8
@@ -88,7 +87,6 @@ ENV ROCKET_ENV "staging"
 ENV ROCKET_PORT=80
 ENV ROCKET_WORKERS=10
 
-
 # Install needed libraries
 RUN apt-get update && apt-get install -y \
     --no-install-recommends \

docker/amd64/postgresql/Dockerfile.alpine

@@ -82,7 +82,6 @@ ENV ROCKET_PORT=80
 ENV ROCKET_WORKERS=10
 ENV SSL_CERT_DIR=/etc/ssl/certs
 
-
 # Install needed libraries
 RUN apk add --no-cache \
         openssl \

docker/amd64/sqlite/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8
@@ -82,7 +81,6 @@ ENV ROCKET_ENV "staging"
 ENV ROCKET_PORT=80
 ENV ROCKET_WORKERS=10
 
-
 # Install needed libraries
 RUN apt-get update && apt-get install -y \
     --no-install-recommends \

docker/amd64/sqlite/Dockerfile.alpine

@@ -76,7 +76,6 @@ ENV ROCKET_PORT=80
 ENV ROCKET_WORKERS=10
 ENV SSL_CERT_DIR=/etc/ssl/certs
 
-
 # Install needed libraries
 RUN apk add --no-cache \
         openssl \

docker/armv6/mysql/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8

docker/armv6/sqlite/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8

docker/armv7/mysql/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8

docker/armv7/sqlite/Dockerfile

@@ -8,7 +8,6 @@ ENV VAULT_VERSION "v2.12.0b"
 
 ENV URL "https://github.com/dani-garcia/bw_web_builds/releases/download/$VAULT_VERSION/bw_web_$VAULT_VERSION.tar.gz"
 
-
 # Build time options to avoid dpkg warnings and help with reproducible builds.
 ARG DEBIAN_FRONTEND=noninteractive
 ARG LANG=C.UTF-8