Address more code review comments

Author: julian-elastic

test/external-modules/esql-heap-attack/src/javaRestTest/java/org/elasticsearch/xpack/esql/heap_attack/HeapAttackIT.java

@@ -776,7 +776,6 @@ public void testLookupExplosionManyMatches() throws IOException {
     }
 
     public void testLookupExplosionManyMatchesExpression() throws IOException {
-        // 1500, 10000 is enough locally, but some CI machines need more.
         int lookupEntries = 10000;
         assertCircuitBreaks(attempt -> lookupExplosion(attempt * 1500, lookupEntries, 1, lookupEntries, true));
     }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/enrich/LookupFromIndexService.java

@@ -337,7 +337,7 @@ public void writeTo(StreamOutput out) throws IOException {
                 planOut.writeOptionalNamedWriteable(joinOnConditions);
             } else {
                 if (joinOnConditions != null) {
-                    throw new EsqlIllegalArgumentException("LOOKUP JOIN with ON conditions is not supported on remote node");
+                    throw new IllegalArgumentException("LOOKUP JOIN with ON conditions is not supported on remote node");
                 }
             }
         }

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plan/logical/join/JoinConfig.java

@@ -12,7 +12,6 @@
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.core.Nullable;
-import org.elasticsearch.xpack.esql.EsqlIllegalArgumentException;
 import org.elasticsearch.xpack.esql.core.capabilities.Resolvables;
 import org.elasticsearch.xpack.esql.core.expression.Attribute;
 import org.elasticsearch.xpack.esql.core.expression.Expression;
@@ -61,7 +60,7 @@ public void writeTo(StreamOutput out) throws IOException {
         if (out.getTransportVersion().onOrAfter(TransportVersions.ESQL_LOOKUP_JOIN_ON_EXPRESSION)) {
             out.writeOptionalNamedWriteable(joinOnConditions);
         } else if (joinOnConditions != null) {
-            throw new EsqlIllegalArgumentException("LOOKUP JOIN with ON conditions is not supported on remote node");
+            throw new IllegalArgumentException("LOOKUP JOIN with ON conditions is not supported on remote node");
         }
     }
 

x-pack/plugin/esql/src/main/java/org/elasticsearch/xpack/esql/plan/physical/LookupJoinExec.java

@@ -11,7 +11,6 @@
 import org.elasticsearch.common.io.stream.NamedWriteableRegistry;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
-import org.elasticsearch.xpack.esql.EsqlIllegalArgumentException;
 import org.elasticsearch.xpack.esql.core.expression.Attribute;
 import org.elasticsearch.xpack.esql.core.expression.AttributeSet;
 import org.elasticsearch.xpack.esql.core.expression.Expression;
@@ -80,7 +79,7 @@ public void writeTo(StreamOutput out) throws IOException {
         if (out.getTransportVersion().onOrAfter(TransportVersions.ESQL_LOOKUP_JOIN_ON_EXPRESSION)) {
             out.writeOptionalNamedWriteable(joinOnConditions);
         } else if (joinOnConditions != null) {
-            throw new EsqlIllegalArgumentException("LOOKUP JOIN with ON conditions is not supported on remote node");
+            throw new IllegalArgumentException("LOOKUP JOIN with ON conditions is not supported on remote node");
         }
     }