Add AZD_SKIP_UPDATE_CHECK to prevent azd update checks which will enc…

…ourage the user to attempt an install process that, if unmodified, will always fail.

linux/tools.Dockerfile

@@ -46,6 +46,9 @@ RUN tdnf update -y && bash ./tdnfinstall.sh \
 
 # Install azure-developer-cli (azd)
 RUN curl -fsSL https://aka.ms/install-azd.sh | bash
+# Disable update check which would prompt the user to run an install command 
+# that always fails
+ENV AZD_SKIP_UPDATE_CHECK=true
 
 RUN mkdir -p /usr/cloudshell
 WORKDIR /usr/cloudshell