[SPARK-24757][SQL] Improving the error message for broadcast timeouts

## What changes were proposed in this pull request?

In the PR, I propose to provide a tip to user how to resolve the issue of timeout expiration for broadcast joins. In particular, they can increase the timeout via **spark.sql.broadcastTimeout** or disable the broadcast at all by setting **spark.sql.autoBroadcastJoinThreshold** to `-1`.

## How was this patch tested?

It tested manually from `spark-shell`:
```
scala> spark.conf.set("spark.sql.broadcastTimeout", 1)
scala> val df = spark.range(100).join(spark.range(15).as[Long].map { x =>
               Thread.sleep(5000)
               x
            }).where("id = value")
scala> df.count()
```
```
org.apache.spark.SparkException: Could not execute broadcast in 1 secs. You can increase the timeout for broadcasts via spark.sql.broadcastTimeout or disable broadcast join by setting spark.sql.autoBroadcastJoinThreshold to -1
  at org.apache.spark.sql.execution.exchange.BroadcastExchangeExec.doExecuteBroadcast(BroadcastExchangeExec.scala:150)
```

Author: Maxim Gekk <maxim.gekk@databricks.com>

Closes #21727 from MaxGekk/broadcast-timeout-error.

Author: MaxGekk

sql/core/src/main/scala/org/apache/spark/sql/execution/exchange/BroadcastExchangeExec.scala

@@ -17,6 +17,8 @@
 
 package org.apache.spark.sql.execution.exchange
 
+import java.util.concurrent.TimeoutException
+
 import scala.concurrent.{ExecutionContext, Future}
 import scala.concurrent.duration._
 import scala.util.control.NonFatal
@@ -140,7 +142,16 @@ case class BroadcastExchangeExec(
   }
 
   override protected[sql] def doExecuteBroadcast[T](): broadcast.Broadcast[T] = {
-    ThreadUtils.awaitResult(relationFuture, timeout).asInstanceOf[broadcast.Broadcast[T]]
+    try {
+      ThreadUtils.awaitResult(relationFuture, timeout).asInstanceOf[broadcast.Broadcast[T]]
+    } catch {
+      case ex: TimeoutException =>
+        logError(s"Could not execute broadcast in ${timeout.toSeconds} secs.", ex)
+        throw new SparkException(s"Could not execute broadcast in ${timeout.toSeconds} secs. " +
+          s"You can increase the timeout for broadcasts via ${SQLConf.BROADCAST_TIMEOUT.key} or " +
+          s"disable broadcast join by setting ${SQLConf.AUTO_BROADCASTJOIN_THRESHOLD.key} to -1",
+          ex)
+    }
   }
 }