DOC: remove temporary okwarning/okexcept
In our quest to a warning free doc build, we added some temporary okexcept/okwarning in https://github.com/pandas-dev/pandas/pull/26810:

- [ ] okwarning for parquet/feather examples should be removed once the latest version of pyarrow is used in the doc build
- [x] the okexcept in missing_data.rst (https://github.com/pandas-dev/pandas/pull/26810/files#diff-239ec95d581257ed256954660663b277R461) should be removed once https://github.com/pandas-dev/pandas/issues/26778 is fixed
- [x] the okwarning in 10min for the plotting (added in https://github.com/pandas-dev/pandas/pull/26852), which should get fixed by https://github.com/pandas-dev/pandas/pull/26770