dns_interceptor binary in Dockerfile is not architecture-aware (ARM builds fail)

[desmond-45]

Summary
The Dockerfile is currently using an architecture-aware download URL pattern for most binaries (e.g., nsutil, pause, etc.), but the dns_interceptor binary is downloaded using a hardcoded URL and filename that does not specify architecture. This means that ARM builds receive the x86_64 binary, which does not run successfully on ARM clusters.

Steps to Reproduce

1. Build the litmus-go Docker image on an ARM (arm64) system/cluster.
2. During the build phase, the Dockerfile runs:

   curl -L https://github.com/litmuschaos/test-tools/releases/download/${LITMUS_VERSION}/dns_interceptor --output /sbin/dns_interceptor

   There is no architecture variable in the path or filename.
3. The resulting dns_interceptor binary is not compatible with ARM and fails to execute.

Expected Behavior

• The Dockerfile should use an architecture-aware pattern for dns_interceptor, e.g.:

  curl -L https://github.com/litmuschaos/test-tools/releases/download/${LITMUS_VERSION}/dns_interceptor-linux-${TARGETARCH} --output /sbin/dns_interceptor

• The published release assets for dns_interceptor should include ARM-compatible binaries (e.g., dns_interceptor-linux-arm64).

Actual Behavior

• The ARM build receives the x86_64 dns_interceptor binary, leading to failure on ARM clusters.
• Other binaries in the Dockerfile use the ${TARGETARCH} variable correctly.

Additional Info

• Some recent releases of litmuschaos/test-tools do publish multi-arch builds:
  https://github.com/litmuschaos/test-tools/releases
• The Dockerfile should be updated to use the same architecture awareness for dns_interceptor as other binaries.
• This issue impacts DNS experiments on ARM clusters.

Suggested Fix

1. Add architecture awareness in the dns_interceptor URL (as shown above).
2. Ensure that multi-arch dns_interceptor binaries are published to GitHub Releases for each version.