armv5 CI builds are not actually building armv5 binaries

[headius]

It seems the armv5 target to our cross-platform linux builds are not actually building the armv5 binary, and instead just falling back to x86_64.

From a recent build:

-build-native-library:
     [exec] Configuring libffi for x86_64-linux
     [exec] make -C /work/build/jni/libffi-x86_64-linux
     [exec] make[1]: Entering directory '/work/build/jni/libffi-x86_64-linux'
     [exec] make  all-recursive
     [exec] make[2]: Entering directory '/work/build/jni/libffi-x86_64-linux'
     [exec] Making all in include

It appears to be failing to find the armv5 Debian image needed for the build:

Run docker pull --platform $(echo linux-arm-v5 | sed 's|-|/|g') "$DOCKER_IMAGE_NAME" || true
  docker pull --platform $(echo linux-arm-v5 | sed 's|-|/|g') "$DOCKER_IMAGE_NAME" || true
  shell: /usr/bin/bash -e {0}
  env:
    DOCKER_IMAGE_NAME: debian:10
10: Pulling from library/debian
no matching manifest for linux/arm/v5 in the manifest list entries

I will disable this build until we can fix the issue, so there's no confusion about what artifacts it produces.