jetbrains: fix JRE configuration for devcontainer development

[atishnazir]

Description of changes

Jetbrains IDEs download the remote client GUI on each invocation. This client is not patched for Nix and includes its own JDK. JDK selection can be overridden through environment variable (to a Nix patched version).

Previously this was done with JETBRAINSCLIENT_JDK, now it should be done with JETBRAINS_CLIENT_JDK.

See previous PR #195132.

Without this change when trying to start a devcontainer session with either IntelliJ Ultimate or Jetbrains Gateway fails due to attempting to invoke the internally bundled JRE.

Things done

Set JETBRAINS_CLIENT_JDK in addition to JETBRAINSCLIENT_JDK to preserve inconsistent behaviour of downloaded clients.

• Built on platform(s)
  • x86_64-linux
  • aarch64-linux
  • x86_64-darwin
  • aarch64-darwin

Manually tested with the following environment:

nix-shell -I nixpkgs=$NIXPKGS -p jetbrains.gateway -p jetbrains.idea-ultimate 

Checked that IntelliJ Ultimate and Jetbrains Gateway is able to start a devcontainer for the Jetbrains sample project and author's own Go based projects.

Using following script to check environment variables were set as expected:

cat /proc/$(pgrep -f JetBrainsClient)/environ | xargs -0 -n1 echo | grep  JDK
JDK_HOME=/nix/store/a9hjq76qi7acm4pfi928ih7z70d5bndj-jetbrains-jdk-jcef-17.0.8-b1000.8/lib/openjdk
IDEA_JDK=/nix/store/a9hjq76qi7acm4pfi928ih7z70d5bndj-jetbrains-jdk-jcef-17.0.8-b1000.8/lib/openjdk
JETBRAINSCLIENT_JDK=/nix/store/a9hjq76qi7acm4pfi928ih7z70d5bndj-jetbrains-jdk-jcef-17.0.8-b1000.8/lib/openjdk
JETBRAINS_CLIENT_JDK=/nix/store/a9hjq76qi7acm4pfi928ih7z70d5bndj-jetbrains-jdk-jcef-17.0.8-b1000.8/lib/openjdk

[atishnazir]

When checking my PR references, I see that this duplicates #249699