AB#125030 Drop transport-encoding headers in response.

[buckett]

If Canvas sends transport encoding headers we should drop them as we will manage our own transport encoding back to the client.

[Copilot]

Pull request overview

Updates the Canvas proxy response handling to avoid forwarding upstream transport-level response headers, ensuring this service controls how responses are encoded back to clients.

Changes:

• Strips Transfer-Encoding from proxied responses (in addition to already stripping Set-Cookie).
• Adds an inline comment explaining why the header is removed.

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[Copilot]

Just as a heads up, I was blocked by some firewall rules while working on your feedback. Expand below for details.

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• cdn.jsdelivr.net
  • Triggering command: /usr/lib/jvm/temurin-21-jdk-amd64/bin/java /usr/lib/jvm/temurin-21-jdk-amd64/bin/java -jar /home/REDACTED/work/tool-support/tool-support/target/surefire/surefirebooter-20260520093500163_3.jar /home/REDACTED/work/tool-support/tool-support/target/surefire 2026-05-20T09-34-59_703-jvmRun1 surefire-20260520093500163_1tmp surefire_0-20260520093500163_2tmp (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)