Make the delineation between `DailyEquityHistoryTestCase` and
`MinuteEquityHistoryTestCase` whether or not minute dts or daily dts are
used as the query timestamp, instead of whether the frequency is `1d`
vs. `1m`.
Preparing for adding a repro case for where using `1d` with minute data
fails when there is an adjustment occuring the day before the query
minute dt.