Remove unnecessary components from devcontainer

We had some things in the devcontainer that are necessary for the runtime repo, but not for roslyn.

.devcontainer/Dockerfile

@@ -6,16 +6,4 @@ FROM mcr.microsoft.com/vscode/devcontainers/dotnet:0-${VARIANT}
 
 # Set up machine requirements to build the repo
 RUN apt-get update && export DEBIAN_FRONTEND=noninteractive \
-    && apt-get -y install --no-install-recommends cmake llvm-9 clang-9 \
-        build-essential python curl git lldb-6.0 liblldb-6.0-dev \
-        libunwind8 libunwind8-dev gettext libicu-dev liblttng-ust-dev \
-        libssl-dev libnuma-dev libkrb5-dev zlib1g-dev ninja-build
-
-# Install V8 Engine
-SHELL ["/bin/bash", "-c"]
-
-RUN curl -sSL "https://netcorenativeassets.blob.core.windows.net/resource-packages/external/linux/chromium-v8/v8-linux64-rel-8.5.183.zip" -o ./v8.zip \
-    && unzip ./v8.zip -d /usr/local/v8 \
-    && echo $'#!/usr/bin/env bash\n\
-"/usr/local/v8/d8" --snapshot_blob="/usr/local/v8/snapshot_blob.bin" "$@"\n' > /usr/local/bin/v8 \
-    && chmod +x /usr/local/bin/v8
+    && apt-get -y install --no-install-recommends curl git