[V0 Deprecation] Remove V0 metrics code (#27215)

Signed-off-by: Nick Hill <nhill@redhat.com>

vllm/engine/metrics_types.py

-# SPDX-License-Identifier: Apache-2.0
-# SPDX-FileCopyrightText: Copyright contributors to the vLLM project
-"""
-These types are defined in this file to avoid importing vllm.engine.metrics
-and therefore importing prometheus_client.
-
-This is required due to usage of Prometheus multiprocess mode to enable
-metrics after splitting out the uvicorn process from the engine process.
-
-Prometheus multiprocess mode requires setting PROMETHEUS_MULTIPROC_DIR
-before prometheus_client is imported. Typically, this is done by setting
-the env variable before launch, but since we are a library, we need to
-do this in Python code and lazily import prometheus_client.
-"""
-
-import time
-from abc import ABC, abstractmethod
-from dataclasses import dataclass
-
-from vllm.config import SupportsMetricsInfo, VllmConfig
-
-
-@dataclass
-class Stats:
-    """Created by LLMEngine for use by StatLogger."""
-
-    now: float
-
-    # System stats (should have _sys suffix)
-    #   Scheduler State
-    num_running_sys: int
-    num_waiting_sys: int
-    num_swapped_sys: int
-    #   KV Cache Usage in %
-    gpu_cache_usage_sys: float
-    cpu_cache_usage_sys: float
-    #   Prefix caching block hit rate
-    cpu_prefix_cache_hit_rate: float
-    gpu_prefix_cache_hit_rate: float
-
-    # Iteration stats (should have _iter suffix)
-    num_prompt_tokens_iter: int
-    num_generation_tokens_iter: int
-    num_tokens_iter: int
-    time_to_first_tokens_iter: list[float]
-    inter_token_latencies_iter: list[float]
-    num_preemption_iter: int
-
-    # Request stats (should have _requests suffix)
-    #   Latency
-    time_e2e_requests: list[float]
-    time_queue_requests: list[float]
-    time_inference_requests: list[float]
-    time_prefill_requests: list[float]
-    time_decode_requests: list[float]
-    #   Metadata
-    num_prompt_tokens_requests: list[int]
-    num_generation_tokens_requests: list[int]
-    n_requests: list[int]
-    max_num_generation_tokens_requests: list[int]
-    max_tokens_requests: list[int]
-    finished_reason_requests: list[str]
-    waiting_lora_adapters: list[str]
-    running_lora_adapters: list[str]
-    max_lora: str
-
-
-class StatLoggerBase(ABC):
-    """Base class for StatLogger."""
-
-    def __init__(self, local_interval: float, vllm_config: VllmConfig) -> None:
-        # Tracked stats over current local logging interval.
-        self.num_prompt_tokens: list[int] = []
-        self.num_generation_tokens: list[int] = []
-        self.last_local_log = time.time()
-        self.local_interval = local_interval
-
-    @abstractmethod
-    def log(self, stats: Stats) -> None:
-        raise NotImplementedError
-
-    @abstractmethod
-    def info(self, type: str, obj: SupportsMetricsInfo) -> None:
-        raise NotImplementedError