[Java] Remove legacy vector classes

[asfimport]

Per discussion during Arrow sync, we might be able to remove the legacy vectors if Dremio can rebase on Arrow master.

This means we will remove the legacy class templates.

It'd great to remove them before 0.8 release, but it's Ok if pushed to 0.9.

Reporter: Li Jin / @icexelloss
Assignee: Bryan Cutler / @BryanCutler

_{Note: This issue was originally created as ARROW-1819. Please see the migration documentation for further details.}

[asfimport]

Siddharth Teotia / @siddharthteotia:
I have already done this as part of ARROW-1476

[asfimport]

Siddharth Teotia / @siddharthteotia:
FIxed as part of #1316

[asfimport]

Li Jin / @icexelloss:
Awesome. I remember we had accessor/mutator methods in new vectors for the legacy vectors to work. Are those removed as well?

[asfimport]

Li Jin / @icexelloss:
@siddharthteotia I don't believe this task is done. This meant to be removing the legacy vector templates.

[asfimport]

Li Jin / @icexelloss:
This is done by 689bbd7