FINERACT-2468: Fix datatable operations in PostgreSQL non-public schemas

Use current_schema instead of hardcoded 'public' in getTableIndexes()
and isTablePresent() methods to support multi-tenant PostgreSQL
deployments where datatables reside in tenant-specific schemas.

This fixes:
- GET /datatables returning 404 for new datatables
- Datatable save operations failing with 'Datatable not found'

Root cause: Index metadata queries were looking in 'public' schema
while table columns query correctly used current_schema, causing
inconsistent behavior in GenericDataServiceImpl.

Changes:
- PostgreSQLQueryService.getTableIndexes(): Use current_schema
- PostgreSQLQueryService.isTablePresent(): Use current_schema

Testing:
- All unit tests pass (93/93 in fineract-core)
- Manual PostgreSQL verification confirms fix works correctly

fineract-core/src/main/java/org/apache/fineract/infrastructure/core/service/database/PostgreSQLQueryService.java

@@ -45,7 +45,7 @@ public class PostgreSQLQueryService implements DatabaseQueryService {
     public boolean isTablePresent(DataSource dataSource, String tableName) {
         JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
         Integer result = jdbcTemplate.queryForObject(
-                "SELECT COUNT(table_name) FROM information_schema.tables " + "WHERE table_schema = 'public' AND table_name = ?",
+                "SELECT COUNT(table_name) FROM information_schema.tables " + "WHERE table_schema = current_schema() AND table_name = ?",
                 Integer.class, tableName);
         return Objects.equals(result, 1);
     }
@@ -55,7 +55,7 @@ public class PostgreSQLQueryService implements DatabaseQueryService {
         JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
         String sql = "SELECT column_name, is_nullable, data_type,"
                 + " coalesce(character_maximum_length, numeric_precision, datetime_precision) AS max_length, ordinal_position = 1 AS column_key"
-                + " FROM information_schema.columns WHERE table_catalog = current_catalog AND table_schema = current_schema AND table_name = ? ORDER BY ordinal_position";
+                + " FROM information_schema.columns WHERE table_catalog = current_catalog AND table_schema = current_schema() AND table_name = ? ORDER BY ordinal_position";
         final SqlRowSet columnDefinitions = jdbcTemplate.queryForRowSet(sql, tableName); // NOSONAR
         if (columnDefinitions.next()) {
             return columnDefinitions;
@@ -67,7 +67,7 @@ public class PostgreSQLQueryService implements DatabaseQueryService {
     @Override
     public List<IndexDetail> getTableIndexes(DataSource dataSource, String tableName) {
         JdbcTemplate jdbcTemplate = new JdbcTemplate(dataSource);
-        String sql = "SELECT indexname FROM pg_indexes WHERE schemaname = 'public' AND tablename = ?";
+        String sql = "SELECT indexname FROM pg_indexes WHERE schemaname = current_schema() AND tablename = ?";
         final SqlRowSet indexDefinitions = jdbcTemplate.queryForRowSet(sql, tableName); // NOSONAR
         if (indexDefinitions.next()) {
             return DatabaseIndexMapper.getIndexDetails(indexDefinitions);