TST: full dtype tests for .drop_duplicates and .duplicated

[jreback]

#15738 (comment)
xref #15738

we exercise tests for .drop_duplicates & .duplicated in various places

• for series -> pandas/tests/series/test_analytics.py
• for dataframe -> pandas/test/frame/test_analytics.py
• for index -> pandas/tests/test_base.py
• datetimes -> pandas/tests//indexes/datetimes/test_ops.py
• period -> pandas/tests//indexes/period/test_ops.py
• categorical -> pandas/tests//test_categorical.py
• timedelta -> pandas/tests//indexes/timedeltas/test_ops.py

I think we are a little light on the categorical ones (esp need to exercise with categories of int, datetime, timedelta, bool)

bool and a battery that covers all int & uint & float would be nice as well.

could certainly take multiple PR's to close this issue (if multiple people want to do this).

[jamestran201]

Hi, could someone take a look at the test cases added in PR 17974? The test cases are for Series. If they are OK, I'll do the same to the remaining tests.
#17974