Reduce num docs in ValuesSourceReaderOperatorTests (#100469)

The test failed because it took more than 30 seconds to extract fields 
for approximately 100,000 documents. With the randomized page size, we
can make these tests more reliable and faster by reducing the number of
documents.

Closes #100235

x-pack/plugin/esql/compute/src/test/java/org/elasticsearch/compute/lucene/ValuesSourceReaderOperatorTests.java

@@ -202,7 +202,7 @@ public class ValuesSourceReaderOperatorTests extends OperatorTestCase {
         DriverContext driverContext = driverContext();
         loadSimpleAndAssert(
             driverContext,
-            CannedSourceOperator.collectPages(simpleInput(driverContext.blockFactory(), between(1_000, 100 * 1024)))
+            CannedSourceOperator.collectPages(simpleInput(driverContext.blockFactory(), between(100, 5000)))
         );
     }
 
@@ -212,7 +212,7 @@ public class ValuesSourceReaderOperatorTests extends OperatorTestCase {
             driverContext,
             List.of(
                 CannedSourceOperator.mergePages(
-                    CannedSourceOperator.collectPages(simpleInput(driverContext.blockFactory(), between(1_000, 100 * 1024)))
+                    CannedSourceOperator.collectPages(simpleInput(driverContext.blockFactory(), between(100, 5000)))
                 )
             )
         );
@@ -226,7 +226,7 @@ public class ValuesSourceReaderOperatorTests extends OperatorTestCase {
     public void testLoadAllInOnePageShuffled() {
         DriverContext driverContext = driverContext();
         Page source = CannedSourceOperator.mergePages(
-            CannedSourceOperator.collectPages(simpleInput(driverContext.blockFactory(), between(1_000, 100 * 1024)))
+            CannedSourceOperator.collectPages(simpleInput(driverContext.blockFactory(), between(100, 5000)))
         );
         List<Integer> shuffleList = new ArrayList<>();
         IntStream.range(0, source.getPositionCount()).forEach(i -> shuffleList.add(i));
@@ -384,7 +384,7 @@ public class ValuesSourceReaderOperatorTests extends OperatorTestCase {
         NumericDocValuesField intField = new NumericDocValuesField(intFt.name(), 0);
         NumericDocValuesField longField = new NumericDocValuesField(longFt.name(), 0);
         NumericDocValuesField doubleField = new DoubleDocValuesField(doubleFt.name(), 0);
-        final int numDocs = 100_000;
+        final int numDocs = between(100, 5000);
         try (RandomIndexWriter w = new RandomIndexWriter(random(), directory)) {
             Document doc = new Document();
             for (int i = 0; i < numDocs; i++) {