Use combiner's calculate_new_intervals for target_final_intervals (#8603

)

This should work around a rare error in `_calculate_new_intervals` that
could generate invalid partitioners in a way that
`calculate_new_intervals` cannot.

scripts/variantstore/wdl/extract/import_gvs.py

@@ -2,7 +2,7 @@
 from typing import List
 
 import hail as hl
-from hail.vds.combiner.combine import merge_alleles
+from hail.vds.combiner.combine import merge_alleles, calculate_new_intervals
 from hail.genetics.reference_genome import reference_genome_type
 from hail.typecheck import typecheck, sequenceof, numeric
 
@@ -297,7 +297,8 @@ def convert_array_with_id_keys_to_dense_array(arr, ids, drop=[]):
     target_records = first_ref_mt.count_rows() // total_partitions
     info(f'import_gvs: using target_records (records per partition) of {target_records} for VDS merge')
 
-    target_final_intervals = first_ref_mt._calculate_new_partitions(total_partitions)
+    interval_tmp = os.path.join(tmp_dir, 'interval_checkpoint.ht')
+    target_final_intervals = calculate_new_intervals(first_ref_mt, target_records, interval_tmp)
 
     with hl._with_flags(no_whole_stage_codegen='1'):