Remove no-render-return-value from recommended

[bz2]

This rules is about a potential future change to a ReactDOM interface
not any actual problem, and is the slowest plugin:react/recommended
by a factor of about 3.

Timings from one of our projects:

Rule                           | Time (ms) | Relative
:------------------------------|----------:|--------:
import/namespace               |  5505.442 |    19.3%
indent                         |  4169.809 |    14.6%
react/no-render-return-value   |  3402.119 |    11.9%
import/named                   |  1252.616 |     4.4%
react/no-deprecated            |  1165.668 |     4.1%
react/display-name             |  1126.994 |     4.0%
react/no-direct-mutation-state |  1109.049 |     3.9%
react/sort-comp                |   691.149 |     2.4%
react/no-string-refs           |   680.091 |     2.4%
import/default                 |   622.367 |     2.2%

Removing the rule does save 4s from a 60s run.

[bz2]

Appveyor failed but only one platform and looks spurious:

Environment: nodejs_version=8; Platform: x64
Build started
Fetching repository commit (873816e)...An error occurred while sending the request.

[ljharb]

I don't think "slowest" should be a disqualifier from whether it's recommended; it's a lint run in CI.

[ljharb]

Separately, this is an actual problem for future migrations, so it seems useful to keep recommended.

As for it being slow, it doesn't seem like it should be - making it faster would be great tho!

[yannickcr]

Closing since performance problem was likely fixed in #2264

[bz2]

I still think this is not a good rule to enable by default, but thanks @golopot for making it less painful.

There's no harm in code just failing when an actual migration happens. I have two instances of ReactDOM.render() in my entire codebase, this isn't a thing it makes sense to check every line in the project for.