DEPR: deprecate .as_blocks()
closes #17302

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=h1) Report
> Merging [#17656](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/965c1c89b6df471d88dc0e1188fb8cbc0d89f867?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `66.66%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17656/graphs/tree.svg?src=pr&width=650&token=eZ4WkYLtcO&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17656      +/-   ##
==========================================
- Coverage   91.26%   91.24%   -0.02%     
==========================================
  Files         163      163              
  Lines       49806    49805       -1     
==========================================
- Hits        45455    45446       -9     
- Misses       4351     4359       +8
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.04% <66.66%> (ø)` | :arrow_up: |
| #single | `40.31% <33.33%> (-0.06%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `92.09% <66.66%> (+0.04%)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.73% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17656?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/17656?src=pr&el=footer). Last update [965c1c8...16706f7](https://codecov.io/gh/pandas-dev/pandas/pull/17656?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/17656?src=pr&el=h1) Report
> Merging [#17656](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/6da85b30d989855fe2a1f5d1323189f0fc639e60?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `93.33%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/17656/graphs/tree.svg?width=650&src=pr&token=eZ4WkYLtcO&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17656      +/-   ##
==========================================
- Coverage   91.26%   91.24%   -0.02%     
==========================================
  Files         163      163              
  Lines       49806    49805       -1     
==========================================
- Hits        45455    45446       -9     
- Misses       4351     4359       +8
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `89.04% <93.33%> (ø)` | :arrow_up: |
| #single | `40.3% <66.66%> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/computation/expressions.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tcHV0YXRpb24vZXhwcmVzc2lvbnMucHk=) | `0% <ø> (ø)` | :arrow_up: |
| [pandas/util/testing.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL3V0aWwvdGVzdGluZy5weQ==) | `100% <ø> (ø)` | :arrow_up: |
| [pandas/core/window.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvd2luZG93LnB5) | `96.37% <100%> (ø)` | :arrow_up: |
| [pandas/core/internals.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvaW50ZXJuYWxzLnB5) | `94.3% <100%> (+0.01%)` | :arrow_up: |
| [pandas/core/generic.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZ2VuZXJpYy5weQ==) | `92.07% <87.5%> (+0.02%)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.73% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17656?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/17656?src=pr&el=footer). Last update [6da85b3...aa2d9d6](https://codecov.io/gh/pandas-dev/pandas/pull/17656?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 update, thanks @gfyoung 