CLN: Remove SparseList from pandas API
Deprecated in 0.19.0.

xref #14007.

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=h1) Report
> Merging [#18621](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/6e56195fcb021e7c53301722804087ef2a83bc39?src=pr&el=desc) will **decrease** coverage by `0.02%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18621/graphs/tree.svg?src=pr&width=650&token=eZ4WkYLtcO&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18621      +/-   ##
==========================================
- Coverage   91.46%   91.44%   -0.03%     
==========================================
  Files         157      156       -1     
  Lines       51449    51375      -74     
==========================================
- Hits        47060    46979      -81     
- Misses       4389     4396       +7
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.31% <ø> (-0.02%)` | :arrow_down: |
| #single | `40.61% <ø> (-0.1%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/sparse/api.py](https://codecov.io/gh/pandas-dev/pandas/pull/18621/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL2FwaS5weQ==) | `100% <ø> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/18621/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `82.11% <ø> (-0.07%)` | :arrow_down: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18621/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18621/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=footer). Last update [6e56195...c3068b3](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 # [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=h1) Report
> Merging [#18621](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/6e56195fcb021e7c53301722804087ef2a83bc39?src=pr&el=desc) will **decrease** coverage by `0.02%`.
> The diff coverage is `n/a`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/18621/graphs/tree.svg?width=650&height=150&src=pr&token=eZ4WkYLtcO)](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #18621      +/-   ##
==========================================
- Coverage   91.46%   91.44%   -0.03%     
==========================================
  Files         157      156       -1     
  Lines       51449    51375      -74     
==========================================
- Hits        47060    46979      -81     
- Misses       4389     4396       +7
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.31% <ø> (-0.02%)` | :arrow_down: |
| #single | `40.61% <ø> (-0.1%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/sparse/api.py](https://codecov.io/gh/pandas-dev/pandas/pull/18621/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3BhcnNlL2FwaS5weQ==) | `100% <ø> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/18621/diff?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `82.11% <ø> (-0.07%)` | :arrow_down: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/18621/diff?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/18621/diff?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.81% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=continue).
> **Legend** - [Click here to learn more](https://docs.codecov.io/docs/codecov-delta)
> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=footer). Last update [6e56195...c3068b3](https://codecov.io/gh/pandas-dev/pandas/pull/18621?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 thanks!