scbuildstmt: Rerewrite a few function with better APIs

This commit cleaned up a few functions using the preferred .FilterXxx()
API to retrieve element from an element set. No functional change is
introduced.

Informs: cockroachdb#117574
Release note: None

pkg/sql/schemachanger/scbuild/internal/scbuildstmt/alter_table_add_column.go

@@ -725,14 +725,23 @@ func addSecondaryIndexTargetsForAddColumn(
 	}
 }
 
-func mustRetrieveTemporaryIndexElem(
+func retrieveTemporaryIndexElem(
 	b BuildCtx, tableID catid.DescID, indexID catid.IndexID,
 ) (temporaryIndexElem *scpb.TemporaryIndex) {
-	scpb.ForEachTemporaryIndex(b.QueryByID(tableID), func(current scpb.Status, target scpb.TargetStatus, e *scpb.TemporaryIndex) {
+	b.QueryByID(tableID).FilterTemporaryIndex().ForEach(func(
+		_ scpb.Status, _ scpb.TargetStatus, e *scpb.TemporaryIndex,
+	) {
 		if e.IndexID == indexID {
 			temporaryIndexElem = e
 		}
 	})
+	return temporaryIndexElem
+}
+
+func mustRetrieveTemporaryIndexElem(
+	b BuildCtx, tableID catid.DescID, indexID catid.IndexID,
+) (temporaryIndexElem *scpb.TemporaryIndex) {
+	temporaryIndexElem = retrieveTemporaryIndexElem(b, tableID, indexID)
 	if temporaryIndexElem == nil {
 		panic(errors.AssertionFailedf("programming error: cannot find a TemporaryIndex element"+
 			" of ID %v", indexID))

pkg/sql/schemachanger/scbuild/internal/scbuildstmt/alter_table_add_constraint.go

@@ -833,8 +833,16 @@ func ensureColCanBeUsedInInboundFK(b BuildCtx, tableID catid.DescID, columnID ca
 	}
 }
 
+func retrieveTableElem(b BuildCtx, tableID catid.DescID) *scpb.Table {
+	return b.QueryByID(tableID).FilterTable().Filter(func(
+		current scpb.Status, target scpb.TargetStatus, e *scpb.Table,
+	) bool {
+		return e.TableID == tableID
+	}).MustGetZeroOrOneElement()
+}
+
 func mustRetrieveTableElem(b BuildCtx, tableID catid.DescID) *scpb.Table {
-	_, _, tblElem := scpb.FindTable(b.QueryByID(tableID))
+	tblElem := retrieveTableElem(b, tableID)
 	if tblElem == nil {
 		panic(errors.AssertionFailedf("programming error: cannot find a Table element for table %v", tableID))
 	}