CI: disable codecov
xref #27602
Give me ~15 minutes here. Doing some debugging of our config. This may be unnecessary if https://github.com/pandas-dev/pandas/pull/28070 passes. I’m AFK for a bit.  If codecov problem is resolved, feel free to close this. No luck just targeting master (400 error again).

Just disabling. Owee, I'm MrMeeseeks, Look at me.

There seem to be a conflict, please backport manually. Here are approximate instructions:

1. Checkout backport branch and update it.

```
$ git checkout 0.25.x
$ git pull
```

2. Cherry pick the first parent branch of the this PR on top of the older branch:
```
$ git cherry-pick -m1 cf6b09d94d648b4bc3783eb5fff8b3241600528a
```

3. You will likely have some merge/cherry-pick conflict here, fix them and commit:

```
$ git commit -am 'Backport PR #28065: CI: disable codecov'
```

4. Push to a named branch :

```
git push YOURFORK 0.25.x:auto-backport-of-pr-28065-on-0.25.x
```

5. Create a PR against branch 0.25.x, I would have named this PR:

> "Backport PR #28065 on branch 0.25.x"

And apply the correct labels and milestones.

Congratulation you did some good work ! Hopefully your backport PR will be tested by the continuous integration and merged soon!

If these instruction are inaccurate, feel free to [suggest an improvement](https://github.com/MeeseeksBox/MeeseeksDev).
                