Local Ratelimit Added Always Reject Support Via Max Tokens Zero

Added support for always-reject behavior in the :ref:local rate limit filter <config_http_filters_local_rate_limit> by setting max_tokens to 0 in the :ref:token bucket <envoy_v3_api_msg_type.v3.TokenBucket> configuration. This applies to both the default token bucket and per-descriptor token buckets, including wildcard (dynamic) descriptors. When max_tokens is 0, the fill interval validation (minimum 50ms) is also skipped since filling is irrelevant.