fix(integ): repair two pre-existing IT failures on main (opensearch-project#5545)

QueryValidationIT.testAliasToKeywordMultiFieldFailsWithBadRequest: opensearch-project#5532 changed
the SQL error formatter to unwrap ErrorReport to its cause, so the reported type
is now the underlying SemanticCheckException, not the ErrorReport wrapper. Update
the expected error type to match. Query is still correctly rejected (400); only
the envelope type changed.

CalciteExplainIT.testNoMvBasic / testNoMvWithEval: the assertion scanned the full
logical+physical explain YAML for ARRAY_JOIN, but the physical section renders
differently with pushdown disabled (CalciteNoPushdownIT), making the test flaky
on some runners. nomv lowers to MVJOIN -> ARRAY_JOIN, which is stable in the
LOGICAL plan regardless of pushdown (verified with pushdown on and off). Assert
on the logical section only.

Signed-off-by: Eric Wei <mengwei.eric@gmail.com>

Author: mengweieric

integ-test/src/test/java/org/opensearch/sql/calcite/remote/CalciteExplainIT.java

@@ -2888,10 +2888,13 @@ public void testNoMvBasic() throws IOException {
             "source=%s | fields firstname, age | eval names = array(firstname) | nomv names |"
                 + " fields names",
             TEST_INDEX_BANK);
-    var result = explainQueryYaml(query);
+    // Assert on the LOGICAL plan only: nomv lowers to MVJOIN -> ARRAY_JOIN, which is stable in the
+    // logical plan regardless of pushdown. The physical section's rendering varies with the
+    // pushdown setting (e.g. under CalciteNoPushdownIT), so scanning the whole output is flaky.
+    String logical = logicalPlan(explainQueryYaml(query));
     Assert.assertTrue(
-        "Expected explain to contain ARRAY_JOIN function",
-        result.toLowerCase().contains("array_join"));
+        "Expected logical plan to contain ARRAY_JOIN function",
+        logical.toLowerCase().contains("array_join"));
   }
 
   @Test
@@ -2901,10 +2904,24 @@ public void testNoMvWithEval() throws IOException {
             "source=%s | eval full_name = concat(firstname, ' J.') | eval name_array ="
                 + " array(full_name) | nomv name_array | fields name_array",
             TEST_INDEX_BANK);
-    var result = explainQueryYaml(query);
+    String logical = logicalPlan(explainQueryYaml(query)).toLowerCase();
     Assert.assertTrue(
-        "Expected explain to contain both CONCAT and ARRAY_JOIN",
-        result.toLowerCase().contains("concat") && result.toLowerCase().contains("array_join"));
+        "Expected logical plan to contain both CONCAT and ARRAY_JOIN",
+        logical.contains("concat") && logical.contains("array_join"));
+  }
+
+  /**
+   * Return just the {@code logical:} section of a YAML explain result (everything before the {@code
+   * physical:} key). The logical plan is deterministic across pushdown on/off, whereas the physical
+   * section's rendering varies — so assertions on plan content should target the logical plan to
+   * avoid flakiness.
+   *
+   * <p>Splits on the line-anchored top-level {@code "\nphysical:"} key so a string value that
+   * happens to contain {@code "physical:"} inside the logical section can't truncate the plan.
+   */
+  private static String logicalPlan(String explainYaml) {
+    int physicalIdx = explainYaml.indexOf("\nphysical:");
+    return physicalIdx >= 0 ? explainYaml.substring(0, physicalIdx) : explainYaml;
   }
 
   @Test

integ-test/src/test/java/org/opensearch/sql/sql/QueryValidationIT.java

@@ -117,7 +117,10 @@ public void testAliasToKeywordMultiFieldFailsWithBadRequest() throws IOException
 
     expectResponseException()
         .hasStatusCode(BAD_REQUEST)
-        .hasErrorType("ErrorReport")
+        // #5532 unwraps ErrorReport to its cause in the SQL error formatter, so the reported type
+        // is
+        // now the underlying SemanticCheckException, not the ErrorReport wrapper.
+        .hasErrorType("SemanticCheckException")
         .containsMessage("Alias field [source_alias] refers to unresolved path [source.keyword]")
         .whenExecute(String.format(Locale.ROOT, "SELECT * FROM %s", index));
   }