Bump bpf-tools to v1.2 and get rid of xargo

sdk/bpf/rust/xargo-build.sh

@@ -1,29 +0,0 @@
-#!/usr/bin/env bash
-
-bpf_sdk=$(cd "$(dirname "$0")/.." && pwd)
-# shellcheck source=sdk/bpf/env.sh
-source "$bpf_sdk"/env.sh
-
-set -e
-(
-  while true; do
-    if [[ -r Xargo.toml ]]; then
-      break;
-    fi
-    if [[ $PWD = / ]]; then
-      cat <<EOF
-Error: Failed to find Xargo.toml
-
-Please create a Xargo.toml file in the same directory as your Cargo.toml with
-the following contents:
-
-  [target.bpfel-unknown-unknown.dependencies.std]
-  features = []
-
-EOF
-      exit 1
-    fi
-    cd ..
-  done
-)
-exec "$XARGO" build --target "$XARGO_TARGET" --release "$@"