[Tempest] Split up share migration tests to separate classes

All tempest tests that are located in single class always run
serially. And one of our classes that performs lots of different
share migration tests takes about 20 minutes. So, split them up
to separate classes to speed up test run.

Change-Id: I117484f56ef8de9b01db4818be0069e98b6c78fc
Closes-Bug: #1663574
1 file changed
tree: 544f6ed1dc8e77f5c0484c5cf7d16c29ca269cde
  1. manila_tempest_tests/