[VCF] END position does not work for insertions in classifier

[jazzy-y]

For SVclassifier
INFO:END attribute does not appear in output for SVTYPE=INS but works for all other types (DEL, INV, DUP)
The record.stop is recorded but removed when written in record

• Potential PR Fix: Update handling of INFO/END when writing records in VCF pysam-developers/pysam#1201