Removed Panel class from HDF ASVs
This is a logical follow up to #25233 which should also help resolve the build failures in #24953
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25281?src=pr&el=h1) Report
> Merging [#25281](https://codecov.io/gh/pandas-dev/pandas/pull/25281?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/4d44a2aff08c3075d9472e361bd7448a0472494e?src=pr&el=desc) will **not change** coverage.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/25281/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/25281?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #25281   +/-   ##
=======================================
  Coverage   91.72%   91.72%           
=======================================
  Files         173      173           
  Lines       52831    52831           
=======================================
  Hits        48457    48457           
  Misses       4374     4374
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.28% <ø> (ø)` | :arrow_up: |
| #single | `41.72% <ø> (ø)` | :arrow_up: |


------

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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/25281?src=pr&el=footer). Last update [4d44a2a...b5d274d](https://codecov.io/gh/pandas-dev/pandas/pull/25281?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Windows fail looks unrelated.  Re-push? thanks !