storage: make registry redirect cache work

Disable automatic redirect following to allow registry.rs to cache 307 redirect URLs and skip registry
round-trips on subsequent chunk reads from the same blob.

Explicitly disable system proxy when no proxy is configured to ensure direct client connections bypass
HTTP_PROXY/HTTPS_PROXY environment variables, particularly important for fallback operations when
retry_op() sets disable_proxy=true.

Signed-off-by: Peng Tao <bergwolf@hyper.sh>