flatpak-builder cannot find Flatpak SDK in fedora-toolbox-35

**Describe the bug**

Cannot use `flatpak-builder` in Fedora 35 with a `fedora-toolbox-35` container since sdks can't be found.

**Steps how to reproduce the behaviour**
1. Use `flatpak-builder` in a `fedora-toolbox-35` container on Fedora 35 (I used Silverblue).
2. Attempt to build an app with any Flatpak SDK (I tried with GNOME SDK, probably affects others).
3. You will see `Failed to init: Unable to find sdk org.gnome.Sdk version 40` regardless of whether the sdk is installed on the host or not.
4. I am not able to install `flatpak` correctly either, but I think this was a problem in `fedora-toolbox-34` and Fedora 34 as well. But this issue was only introduced in 35, even when https://github.com/containers/toolbox/issues/629 existed before.

**Expected behaviour**
`flatpak-builder` finds needed sdks as expected.

**Actual behaviour**
`flatpak-builder` is effectively useless without its sdks in a `fedora-toolbox-35` container

**Output of `toolbox --version` (v0.0.90+)**
`toolbox version 0.0.99.2`

**Toolbox package info (`rpm -q toolbox`)**
`toolbox-0.0.99.2^3.git075b9a8d2779-1.fc35.x86_64`

**Output of `podman version`**
```
Version: 3.3.0
API Version: 3.3.0
Go Version: go1.16.6
Built: Fri Aug 20 12:35:44 2021
OS/Arch: linux/amd64
```

**Podman package info (`rpm -q podman`)**
`podman-3.3.0-1.fc35.x86_64`

**Info about your OS**
Fedora Silverblue 35

**Additional context**
Used fresh fedora-toolbox-35 image.
`flatpak-builder-1.0.12-4.fc35.x86_64`