BUG: LatexFormatter.write_result multi-index
Fixed GH issue 14484:

`LatexFormatter.write_result(...)` now does not print blanks if a
higher-order index differs from the previous row.
Also added testcase for this.

- [X] closes #14484
- [X] tests added / passed
- [X] passes `git diff upstream/master -u -- "*.py" | flake8 --diff`
- [X] whatsnew entry

# [Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17499?src=pr&el=h1) Report
> Merging [#17499](https://codecov.io/gh/pandas-dev/pandas/pull/17499?src=pr&el=desc) into [master](https://codecov.io/gh/pandas-dev/pandas/commit/f11bbf2f505d81900cc83ce387a6a1b1d2a2f866?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/17499/graphs/tree.svg?height=150&width=650&token=eZ4WkYLtcO&src=pr)](https://codecov.io/gh/pandas-dev/pandas/pull/17499?src=pr&el=tree)

```diff
@@            Coverage Diff             @@
##           master   #17499      +/-   ##
==========================================
- Coverage   91.18%   91.17%   -0.02%     
==========================================
  Files         163      163              
  Lines       49543    49547       +4     
==========================================
- Hits        45177    45172       -5     
- Misses       4366     4375       +9
```

| Flag | Coverage Δ | |
|---|---|---|
| #multiple | `88.95% <100%> (ø)` | :arrow_up: |
| #single | `40.21% <0%> (-0.07%)` | :arrow_down: |

| [Impacted Files](https://codecov.io/gh/pandas-dev/pandas/pull/17499?src=pr&el=tree) | Coverage Δ | |
|---|---|---|
| [pandas/io/formats/format.py](https://codecov.io/gh/pandas-dev/pandas/pull/17499?src=pr&el=tree#diff-cGFuZGFzL2lvL2Zvcm1hdHMvZm9ybWF0LnB5) | `96.06% <100%> (+0.01%)` | :arrow_up: |
| [pandas/io/gbq.py](https://codecov.io/gh/pandas-dev/pandas/pull/17499?src=pr&el=tree#diff-cGFuZGFzL2lvL2dicS5weQ==) | `25% <0%> (-58.34%)` | :arrow_down: |
| [pandas/core/frame.py](https://codecov.io/gh/pandas-dev/pandas/pull/17499?src=pr&el=tree#diff-cGFuZGFzL2NvcmUvZnJhbWUucHk=) | `97.77% <0%> (-0.1%)` | :arrow_down: |

------

[Continue to review full report at Codecov](https://codecov.io/gh/pandas-dev/pandas/pull/17499?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/17499?src=pr&el=footer). Last update [f11bbf2...6eadb87](https://codecov.io/gh/pandas-dev/pandas/pull/17499?src=pr&el=lastupdated). Read the [comment docs](https://docs.codecov.io/docs/pull-request-comments).
 @gfyoung Thanks for the comments, it is fixed and green again can you update @jreback : I can carry this one to the finish line. great!

feel free to pick up any PR that is not responsive from the author and can be finished @jreback : Could not push to the remote (permissions), so I opened #18685 .