TST: Remove tests for hdf files created with pandas <= v0.11
- [ x] closes #17375
- [ ] tests added / passed
- [ ] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [x ] whatsnew entry

Tests for old compatability removed because this issue is sufficiently old now, that people should be expected to have solved this by now.

@jreback , the methods ``test_legacy_table_read`` and ``test_legacy_table_write`` don't say if they concern pandas <=0.11 or it's newer compatability issues. It it ok to remove those?

See also discussion in #17375.