Migrate metrics used in flax examples to Evaluate (#18348)

Currently, tensorflow examples use the `load_metric` function from
Datasets library, commit migrates function call to `load` function
from Evaluate library.

examples/flax/text-classification/run_flax_glue.py

@@ -27,9 +27,10 @@ from typing import Any, Callable, Dict, Optional, Tuple
 
 import datasets
 import numpy as np
-from datasets import load_dataset, load_metric
+from datasets import load_dataset
 from tqdm import tqdm
 
+import evaluate
 import jax
 import jax.numpy as jnp
 import optax
@@ -570,9 +571,9 @@ def main():
     p_eval_step = jax.pmap(eval_step, axis_name="batch")
 
     if data_args.task_name is not None:
-        metric = load_metric("glue", data_args.task_name)
+        metric = evaluate.load("glue", data_args.task_name)
     else:
-        metric = load_metric("accuracy")
+        metric = evaluate.load("accuracy")
 
     logger.info(f"===== Starting training ({num_epochs} epochs) =====")
     train_time = 0