[SPARK-32908][SQL] Fix target error calculation in percentile_approx()

### What changes were proposed in this pull request?
1. Change the target error calculation according to the paper [Space-Efficient Online Computation of Quantile Summaries](http://infolab.stanford.edu/~datar/courses/cs361a/papers/quantiles.pdf). It says that the error `e = max(gi, deltai)/2` (see the page 59). Also this has clear explanation [ε-approximate quantiles](http://www.mathcs.emory.edu/~cheung/Courses/584/Syllabus/08-Quantile/Greenwald.html#proofprop1).
2. Added a test to check different accuracies.
3. Added an input CSV file `percentile_approx-input.csv.bz2` to the resource folder `sql/catalyst/src/main/resources` for the test.

### Why are the changes needed?
To fix incorrect percentile calculation, see an example in SPARK-32908.

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

### How was this patch tested?
- By running existing tests in `QuantileSummariesSuite` and in `ApproximatePercentileQuerySuite`.
- Added new test `SPARK-32908: maximum target error in percentile_approx` to `ApproximatePercentileQuerySuite`.

Closes #29784 from MaxGekk/fix-percentile_approx-2.

Authored-by: Max Gekk <max.gekk@gmail.com>
Signed-off-by: HyukjinKwon <gurwls223@apache.org>
(cherry picked from commit 75dd864)
Signed-off-by: HyukjinKwon <gurwls223@apache.org>

sql/catalyst/src/main/scala/org/apache/spark/sql/catalyst/util/QuantileSummaries.scala

@@ -254,7 +254,7 @@ class QuantileSummaries(
 
     // Target rank
     val rank = math.ceil(quantile * count).toLong
-    val targetError = relativeError * count
+    val targetError = sampled.map(s => s.delta + s.g).max / 2
     // Minimum rank at current sample
     var minRank = 0L
     var i = 0

sql/core/src/test/scala/org/apache/spark/sql/ApproximatePercentileQuerySuite.scala

@@ -150,7 +150,7 @@ class ApproximatePercentileQuerySuite extends QueryTest with SharedSparkSession
       (1 to 1000).toDF("col").createOrReplaceTempView(table)
       checkAnswer(
         spark.sql(s"SELECT percentile_approx(col, array(0.25 + 0.25D), 200 + 800) FROM $table"),
-        Row(Seq(499))
+        Row(Seq(500))
       )
     }
   }
@@ -296,4 +296,23 @@ class ApproximatePercentileQuerySuite extends QueryTest with SharedSparkSession
     buffer.quantileSummaries
     assert(buffer.isCompressed)
   }
+
+  test("SPARK-32908: maximum target error in percentile_approx") {
+    withTempView(table) {
+      spark.read
+        .schema("col int")
+        .csv(testFile("test-data/percentile_approx-input.csv.bz2"))
+        .repartition(1)
+        .createOrReplaceTempView(table)
+      checkAnswer(
+        spark.sql(
+          s"""SELECT
+             |  percentile_approx(col, 0.77, 1000),
+             |  percentile_approx(col, 0.77, 10000),
+             |  percentile_approx(col, 0.77, 100000),
+             |  percentile_approx(col, 0.77, 1000000)
+             |FROM $table""".stripMargin),
+        Row(18, 17, 17, 17))
+    }
+  }
 }