libEGL warning failed to create dri screen

## Environment
* OS Version: Ubuntu 20.04
* Source build: Ignition Garden v7.0.0~pre1
* Rendering plugin: ogre2
- System info:
- ```
00:02.0 VGA compatible controller [0300]: Intel Corporation Device [8086:9a60] (rev 01)
01:00.0 VGA compatible controller [0300]: NVIDIA Corporation Device [10de:2520] (rev a1)
```
- ```
OpenGL ES profile version string: OpenGL ES 3.2 NVIDIA 510.54
OpenGL ES profile shading language version string: OpenGL ES GLSL ES 3.20
```
- ```
X.Org X Server 1.20.13
```

## Description
Getting this warning message on a dual GPU machine as well as in Docker.
```
libEGL warning: DRI2: failed to create dri screen
```

[See this related community thread](https://answers.gazebosim.org/question/27597/ignition-crashes-directly-after-start/): forcing ignition to use ogre1 removes that warning message.

Could be ignored but helpful if its removed to avoid confusion.

## Steps to reproduce
Launch the simulator `ign gazebo`