Fix 2.8.x build: remove Jinjava 3.0-only constructs

The previous commit used BaseJinjavaTest.newConfigBuilder() which only
exists in Jinjava 3.0. Replace with JinjavaConfig.newBuilder() plus
matching LegacyOverrides. Also replace Java 16 pattern variable in
instanceof with a traditional approach.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

Author: jasmith-hs

src/main/java/com/hubspot/jinjava/lib/filter/AbstractSetFilter.java

@@ -129,8 +129,8 @@ private boolean potentiallyConvertibleNumbers(Object oneVarObj, Object oneArgObj
   private Set<Object> convertIntegersToLongs(Set<Object> set) {
     Set<Object> result = new LinkedHashSet<>();
     for (Object element : set) {
-      if (element instanceof Integer integer) {
-        result.add(integer.longValue());
+      if (element instanceof Integer) {
+        result.add(Long.valueOf(element.toString()));
       } else {
         result.add(element);
       }

src/test/java/com/hubspot/jinjava/lib/filter/AbstractSetFilterTest.java

@@ -4,6 +4,8 @@
 
 import com.hubspot.jinjava.BaseJinjavaTest;
 import com.hubspot.jinjava.Jinjava;
+import com.hubspot.jinjava.JinjavaConfig;
+import com.hubspot.jinjava.LegacyOverrides;
 import com.hubspot.jinjava.features.BuiltInFeatures;
 import com.hubspot.jinjava.features.FeatureConfig;
 import com.hubspot.jinjava.features.FeatureStrategies;
@@ -102,8 +104,15 @@ public void itDoesNotThrowWarningOnIntegerLongMismatch() {
   @Test
   public void itConvertsIntegerToLongWhenFeatureActive() {
     Jinjava jinjavaWithFeature = new Jinjava(
-      BaseJinjavaTest
-        .newConfigBuilder()
+      JinjavaConfig
+        .newBuilder()
+        .withLegacyOverrides(
+          LegacyOverrides
+            .newBuilder()
+            .withUsePyishObjectMapper(true)
+            .withKeepNullableLoopValues(true)
+            .build()
+        )
         .withFeatureConfig(
           FeatureConfig
             .newBuilder()