API: change default behaviour of str.match from deprecated extract to match (GH5224)
I just stumbled on this, and seems we didn't have this in our deprecations to do list (https://github.com/pandas-dev/pandas/issues/6581).

This PR changes the default behaviour of `str.match` from extracting groups to just a match (True/False). The previous default behaviour was deprecated since 0.13.0 (https://github.com/pandas-dev/pandas/pull/5224)
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15257?src=pr&el=h1) Report
> Merging [#15257](https://codecov.io/gh/pandas-dev/pandas/pull/15257?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/fb7af6e257d5ca162487ea417eae675e3edbe271?src=pr&el=desc) will **decrease** coverage by `0.02%`.
> The diff coverage is `100%`.


```diff
@@            Coverage Diff             @@
##           master   #15257      +/-   ##
==========================================
- Coverage   91.02%   90.99%   -0.03%     
==========================================
  Files         143      143              
  Lines       49403    49396       -7     
==========================================
- Hits        44967    44950      -17     
- Misses       4436     4446      +10
```


| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/15257?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/core/strings.py](https://codecov.io/gh/pandas-dev/pandas/compare/fb7af6e257d5ca162487ea417eae675e3edbe271...0ab36b6d26294bb346a8039945b7a18b91223021?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvc3RyaW5ncy5weQ==) | `98.48% <100%> (-0.02%)` | :arrow_down: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/compare/fb7af6e257d5ca162487ea417eae675e3edbe271...0ab36b6d26294bb346a8039945b7a18b91223021?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/common.py](https://codecov.io/gh/pandas-dev/pandas/compare/fb7af6e257d5ca162487ea417eae675e3edbe271...0ab36b6d26294bb346a8039945b7a18b91223021?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvY29tbW9uLnB5) | `90.96% <0%> (-0.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/compare/fb7af6e257d5ca162487ea417eae675e3edbe271...0ab36b6d26294bb346a8039945b7a18b91223021?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.86% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/15257?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/15257?src=pr&el=footer). Last update [fb7af6e...0ab36b6](https://codecov.io/gh/pandas-dev/pandas/compare/fb7af6e257d5ca162487ea417eae675e3edbe271...0ab36b6d26294bb346a8039945b7a18b91223021?el=footer&src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments). Rebased this (and remove the "as_indexer : ignored" from the docstring). 
@jreback I can't remember if there were others things left to do, but this seems good to go to me. thanks!