`terminal.integrated.shell.linux` setting is deprecated

The `flatpak-warning.txt` provides the following advice:

```
To make the Integrated Terminal automatically use the host system's shell,
you can add this to the settings:

{
"terminal.integrated.shell.linux": "/usr/bin/env",
"terminal.integrated.shellArgs.linux": ["--", "flatpak-spawn", "--host", "bash"]
}
```

To which vs code answers:

> This is deprecated, the new recommended way to configure your default shell is by creating a terminal profile in `#terminal.integrated.profiles.linux#` and setting its profile name as the default in `#terminal.integrated.defaultProfile.linux#`. This will currently take priority over the new profiles settings but that will change in the future.