Fix benchmark-orchestrator image build on linux/arm64

JBang's curl installer tries to download JDK 17 itself and fails on ARM64.
Install SDKMAN first, then use it to install both Java and JBang — SDKMAN
resolves the correct ARM64 binary for both.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: cdhermann

scripts/perf-lab/benchmark-orchestrator.Dockerfile

@@ -32,12 +32,9 @@ RUN . ~/.nvm/nvm.sh && \
     nvm install --lts && \
     nvm use --lts
 
-# Install jbang
-RUN curl -Ls https://sh.jbang.dev | bash -s - app setup
-
-# Install sdkman
-RUN curl -s "https://get.sdkman.io" | bash && \
-    source "$HOME/.sdkman/bin/sdkman-init.sh"
+# Install sdkman, Java, and JBang (SDKMAN handles ARM64 correctly)
+RUN curl -s "https://get.sdkman.io" | bash
+RUN bash -c "source ~/.sdkman/bin/sdkman-init.sh && sdk install java 21.0.5-tem && sdk install jbang"
 
 # Configure homebrew
 # ENV HOMEBREW_PREFIX=/home/linuxbrew/.linuxbrew \