chore: Remove committed RIE binaries and download at build time (#950)

https://datadoghq.atlassian.net/browse/SVLS-8083

## Overview
chore: Remove committed RIE binaries and download at build time
 - Delete local_tests/rie/bottlecap/arm64/rie binary
 - Delete local_tests/rie/bottlecap/x86/rie binary
 - Update Dockerfile to download AWS Lambda RIE from GitHub releases instead of copying local binary
 - Improves maintainability by avoiding committed binaries in version control

## Testing 
Confirmed by local debugging tests

Co-authored-by: tianning.li <tianning.li@datadoghq.com>

Author: litianningdatadog

local_tests/bottlecap/Dockerfile

@@ -32,8 +32,9 @@ RUN curl https://sh.rustup.rs -sSf | bash -s -- -y
 ENV PATH=/root/.cargo/bin:$PATH
 
 
-# The first path is where the custom RIE lives.
-COPY local_tests/rie/${TARGET}/arm64/rie /usr/local/bin/aws-lambda-rie
+# Download the AWS Lambda Runtime Interface Emulator from GitHub releases
+RUN curl -Lo /usr/local/bin/aws-lambda-rie https://github.com/aws/aws-lambda-runtime-interface-emulator/releases/latest/download/aws-lambda-rie-arm64 \
+    && chmod +x /usr/local/bin/aws-lambda-rie
 
 # The first path is the location of your local agent binary
 COPY .binaries/bottlecap-arm64 /opt/extensions/datadog-agent