[SPARK-55757][CORE] Improve spark.task.cpus validation

### What changes were proposed in this pull request?

This PR aim to improve `spark.task.cpus` validation.

### Why are the changes needed?

Currently, Apache Spark throws `java.lang.ArithmeticException` for the invalid `spark.task.cpus`. We had better provide actionable direction.

**BEFORE**
```
$ bin/spark-shell -c spark.task.cpus=0
26/02/28 09:00:56 ERROR SparkContext: Error initializing SparkContext.
java.lang.ArithmeticException: / by zero
	at org.apache.spark.resource.ResourceUtils$.warnOnWastedResources(ResourceUtils.scala:444)
```

**AFTER**
```
$ bin/spark-shell -c spark.task.cpus=0
...
26/02/28 09:02:15 ERROR SparkContext: Error initializing SparkContext.
org.apache.spark.SparkIllegalArgumentException: [INVALID_CONF_VALUE.REQUIREMENT] The value '0' in the config "spark.task.cpus" is invalid. The number of task CPUs must be positive. SQLSTATE: 22022
```

### Does this PR introduce _any_ user-facing change?

This only changes the error message before starting Spark job.

### How was this patch tested?

Pass the CIs with newly added test case.

### Was this patch authored or co-authored using generative AI tooling?

Generated-by: `Gemini 3.1 Pro (High)` on `Antigravity`.

Closes #54559 from dongjoon-hyun/SPARK-55757.

Authored-by: Dongjoon Hyun <dongjoon@apache.org>
Signed-off-by: Dongjoon Hyun <dongjoon@apache.org>

Author: dongjoon-hyun

core/src/main/scala/org/apache/spark/internal/config/package.scala

@@ -711,7 +711,11 @@ package object config {
       .createWithDefault(false)
 
   private[spark] val CPUS_PER_TASK =
-    ConfigBuilder("spark.task.cpus").version("0.5.0").intConf.createWithDefault(1)
+    ConfigBuilder("spark.task.cpus")
+      .version("0.5.0")
+      .intConf
+      .checkValue(_ > 0, "Number of cores to allocate for each task should be positive.")
+      .createWithDefault(1)
 
   private[spark] val DYN_ALLOCATION_ENABLED =
     ConfigBuilder("spark.dynamicAllocation.enabled")

core/src/test/scala/org/apache/spark/SparkContextSuite.scala

@@ -1475,6 +1475,14 @@ class SparkContextSuite extends SparkFunSuite with LocalSparkContext with Eventu
     assert(!sc.conf.get(SparkLauncher.EXECUTOR_EXTRA_JAVA_OPTIONS).contains("-Dfoo=bar"))
     sc.stop()
   }
+
+  test("SPARK-55757: Improve `spark.task.cpus` validation") {
+    val conf = new SparkConf().setAppName("test").setMaster("local").set(CPUS_PER_TASK, 0)
+    val m = intercept[SparkIllegalArgumentException] {
+      sc = new SparkContext(conf)
+    }.getMessage
+    assert(m.contains("Number of cores to allocate for each task should be positive."))
+  }
 }
 
 object SparkContextSuite {