Bug description

In order to run xdebug in ddev, ddev needs the ip of docker's bridge gateway.

During prebuilds, ddev displays an error that the value cannot be determined.
(same is true to opening a workspace after "Skip prebuild" button was pressed, or in case prebuild are failing, and Gitpod workspace open in "prebuild mode" (didn't have a better way to describe it).

Steps to reproduce

1. Open any repo that runs a prebuild, and click "Skip prebuild" button
2. In Gitpod terminal, run docker network inspect bridge
3. Confirm that IPAM.Config.Gateway is missing.

Compare that with a regular workspace, without skipping prebuild, run that same command and you'll see IPAM.Config.Gateway is there.

[
 {
 "Name": "bridge",
 "Id": "73e2ac1b72a1b74a809f0c91c993adc1320ea8de248c189bcbd51c1a49a2edd7",
 "Created": "2022-04-26T15:08:15.608436783Z",
 "Scope": "local",
 "Driver": "bridge",
 "EnableIPv6": false,
 "IPAM": {
 "Driver": "default",
 "Options": null,
 "Config": [
 {
 "Subnet": "172.17.0.0/16",
 }
 ]
 },
 "Internal": false,
 "Attachable": false,
 "Ingress": false,
 "ConfigFrom": {
 "Network": ""
 },
 "ConfigOnly": false,
 "Containers": {},
 "Options": {
 "com.docker.network.bridge.default_bridge": "true",
 "com.docker.network.bridge.enable_icc": "true",
 "com.docker.network.bridge.enable_ip_masquerade": "true",
 "com.docker.network.bridge.host_binding_ipv4": "0.0.0.0",
 "com.docker.network.bridge.name": "docker0",
 "com.docker.network.driver.mtu": "1440"
 },
 "Labels": {}
 }
]

Workspace affected

No response

Expected behavior

No response

Example repository

No response

Anything else?

cc: @jankeromnes, @rfay, @aledbf