Enhance Dockerfiles

* Prevent failure when obj exists from host compile
* Enhance readability of disposed stages
* Formatting

Dockerfile

@@ -3,9 +3,8 @@ ARG DOTNET_VERSION=2
 FROM microsoft/dotnet:${DOTNET_VERSION}-sdk as builder
 WORKDIR /repo
 COPY . .
-RUN export DOTNET_CLI_TELEMETRY_OPTOUT=1 \
- && dotnet clean \
- && dotnet publish \
+ENV DOTNET_CLI_TELEMETRY_OPTOUT=1
+RUN dotnet publish \
     --configuration release \
     --output /jellyfin \
     Jellyfin.Server

Dockerfile.arm

@@ -1,4 +1,4 @@
-# Requires binfm_misc registration for arm                                                               
+# Requires binfm_misc registration
 # https://github.com/multiarch/qemu-user-static#binfmt_misc-register
 ARG DOTNET_VERSION=3.0
 
@@ -11,10 +11,13 @@ RUN tar -xzvf qemu-arm-static.tar.gz
 FROM microsoft/dotnet:${DOTNET_VERSION}-sdk-stretch as builder
 WORKDIR /repo
 COPY . .
+ENV DOTNET_CLI_TELEMETRY_OPTOUT=1
 # TODO Remove or update the sed line when we update dotnet version.
-RUN export DOTNET_CLI_TELEMETRY_OPTOUT=1 \
- && find . -type f -exec sed -i 's/netcoreapp2.1/netcoreapp3.0/g' {} \; \
- && dotnet publish \
+RUN find . -type f -exec sed -i 's/netcoreapp2.1/netcoreapp3.0/g' {} \;
+# Discard objs - may cause failures if exists
+RUN find . -type d -name obj | xargs -r rm -r
+# Build
+RUN dotnet publish \
     -r linux-arm \
     --configuration release \
     --output /jellyfin \

Dockerfile.arm64

@@ -1,4 +1,4 @@
-# Requires binfm_misc registration for aarch64
+# Requires binfm_misc registration
 # https://github.com/multiarch/qemu-user-static#binfmt_misc-register
 ARG DOTNET_VERSION=3.0
 
@@ -12,10 +12,13 @@ RUN tar -xzvf qemu-aarch64-static.tar.gz
 FROM microsoft/dotnet:${DOTNET_VERSION}-sdk-stretch as builder
 WORKDIR /repo
 COPY . .
+ENV DOTNET_CLI_TELEMETRY_OPTOUT=1
 # TODO Remove or update the sed line when we update dotnet version.
-RUN export DOTNET_CLI_TELEMETRY_OPTOUT=1 \
- && find . -type f -exec sed -i 's/netcoreapp2.1/netcoreapp3.0/g' {} \; \
- && dotnet publish \
+RUN find . -type f -exec sed -i 's/netcoreapp2.1/netcoreapp3.0/g' {} \;
+# Discard objs - may cause failures if exists
+RUN find . -type d -name obj | xargs -r rm -r
+# Build
+RUN dotnet publish \
     -r linux-arm64 \
     --configuration release \
     --output /jellyfin \