Add prepare_test_binaries target to Makefile for easier binary downloads

[wlwilliamx]

Currently, we manually run tests/scripts/download-integration-test-binaries.sh to download TiCDC-related binaries for integration testing. To simplify this process, we should add a prepare_test_binaries target in the Makefile, allowing users to run a single make command to download the required binaries.

Proposal

Add the following rule to the Makefile:

prepare_test_binaries:
	./scripts/download-integration-test-binaries.sh "$(branch)" "$(community)" "$(ver)" "$(os)" "$(arch)"

Usage

Users can run:

make prepare_test_binaries

If specific parameters are required, they can be provided as follows:

make prepare_test_binaries community=true ver=v8.0.0 os=linux arch=amd64

This will make it easier for developers and CI pipelines to retrieve the necessary binaries.