vb-15: misc fixes

[nvzm123]

commit vb-15a:
fixes a potential corner-case where hash_id's may not have been unique enough.

commit vb-15b:
allocate/reserve dynamic java heap-space
note: this is somewhat related to rapidsai/cuvs-lucene#139

commit vb-15c:
preserves intermediate pareto data for the purpose of reconstructing graphs quicker

commit vb-15d:

• added forceMerge-versions of nLists and nProbes since those often
  need to be scaled differently depending on segment size
• increased indirect limits on max-segment sizes to account for new abilities of building indexes out-of-core
• fix nanosecond to millisecond conversion truncation error

commit vb-15e:
updated pom.xml

[nvzm123]

cc: @narangvivek10 @kshitizgupta21 @singhmanas1 @cjnolet