TST: Move tests/scripts to scripts/tests
Moves the `tests/scripts` directory to `scripts/tests`, as these tests don't really belong in the top-level `pandas` directory (they test the `scripts` directory, not `pandas`).
# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22531?src=pr&el=h1) Report
> Merging [#22531](https://codecov.io/gh/pandas-dev/pandas/pull/22531?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/98fb53ca2d64658749e9f182b391002ef3500c1b?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/22531/graphs/tree.svg?width=650&token=eZ4WkYLtcO&height=150&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/22531?src=pr&el=tree)

```diff
@@           Coverage Diff           @@
##           master   #22531   +/-   ##
=======================================
  Coverage   92.04%   92.04%           
=======================================
  Files         169      169           
  Lines       50787    50787           
=======================================
  Hits        46745    46745           
  Misses       4042     4042
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `90.45% <ø> (ø)` | :arrow_up: |
| #single | `42.29% <ø> (ø)` | :arrow_up: |


------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22531?src=pr&el=continue).
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> `Δ = absolute <relative> (impact)`, `ø = not affected`, `? = missing data`
> Powered by [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/22531?src=pr&el=footer). Last update [98fb53c...868f6bf](https://codecov.io/gh/pandas-dev/pandas/pull/22531?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 Relevant build:

https://travis-ci.org/pandas-dev/pandas/jobs/421898109 Think we also need to update the Makefile to ensure this still gets linted (?) > Think we also need to update the Makefile to ensure this still gets linted (?)

@WillAyd : AFAICT we don't use the `Makefile` when doing the linting on Travis.  That being said, I don't see why we can't add it as another command. @jreback @datapythonista @WillAyd :

I've addressed all of your comments, and everything is still green!  PTAL. @jreback : Is this good to merge since you approved it? (you generally have merged after approval) yep