CLN: Remove "flake8: noqa" from more files
Another round of house-cleaning that builds off #15842.

xref <a href="https://github.com/pandas-dev/pandas/issues/12066#issuecomment-172285473">#12066  (comment)</a> : the issue remains unresolved, but it does not seem entirely necessary to disable style-checking on the entire file for that IMO.
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=h1) Report
> Merging [#15867](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/d1e1ba08ef259724ba71e0953c52e8e4ad81bd17?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/15867/graphs/tree.svg?src=pr&width=650&token=eZ4WkYLtcO&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #15867      +/-   ##
==========================================
- Coverage   90.98%   90.97%   -0.02%     
==========================================
  Files         143      143              
  Lines       49449    49449              
==========================================
- Hits        44993    44984       -9     
- Misses       4456     4465       +9
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.72% <100%> (ø)` | :arrow_up: |
| #single | `40.65% <100%> (-0.11%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/\_version.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL192ZXJzaW9uLnB5) | `44.65% <ø> (ø)` | :arrow_up: |
| [pandas/tseries/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvY29tbW9uLnB5) | `88.09% <100%> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.56% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15867?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/15867?src=pr&el=footer). Last update [d1e1ba0...632de71](https://codecov.io/gh/pandas-dev/pandas/pull/15867?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/15867?src=pr&el=h1) Report
> Merging [#15867](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/74f527ff0cbc8045b9f350382a4ad37694e8c5e6?src=pr&el=desc) will **decrease** coverage by `0.01%`.
> The diff coverage is `100%`.

[![Impacted file tree graph](https://codecov.io/gh/pandas-dev/pandas/pull/15867/graphs/tree.svg?token=eZ4WkYLtcO&width=650&src=pr&height=150)](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #15867      +/-   ##
==========================================
- Coverage   90.98%   90.97%   -0.02%     
==========================================
  Files         143      143              
  Lines       49449    49449              
==========================================
- Hits        44992    44984       -8     
- Misses       4457     4465       +8
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.72% <100%> (ø)` | :arrow_up: |
| #single | `40.65% <100%> (-0.11%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/\_version.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL192ZXJzaW9uLnB5) | `44.65% <ø> (ø)` | :arrow_up: |
| [pandas/tseries/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL3RzZXJpZXMvY29tbW9uLnB5) | `88.09% <100%> (ø)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.56% <0%> (-0.1%)` | :arrow_down: |
| [pandas/core/common.py](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tbW9uLnB5) | `91.3% <0%> (+0.33%)` | :arrow_up: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15867?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/15867?src=pr&el=footer). Last update [74f527f...0c84926](https://codecov.io/gh/pandas-dev/pandas/pull/15867?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).