Upgrading to 1.63 breaks attaching to Remote Containers over SSH if you have a custom docker executable path configured

• VSCode Version: 1.63
• Local OS Version: Windows 10 19042.1348
• Remote OS Version: Ubuntu 18.04
• Remote Extension/Connection Type: Docker over SSH (e.g. ssh to a remote machine and attach to a container running on that machine)
• Logs:

12265 ms] Remote-Containers 0.209.6 in VS Code 1.63.1 (fe719cd3e5825bf14e14182fddeb88ee8daf044f).
[12264 ms] Start: Run: ssh begillil@############ /bin/sh -c /bin/sh
[12279 ms] Start: Run in host: id -un
[12577 ms] begillil
[12578 ms] 
[12579 ms] Start: Run in host: cat /etc/passwd
[12584 ms] Start: Run in host: echo ~
[12587 ms] /home/begillil
[12587 ms] 
[12588 ms] Start: Run in host: test -x '/home/begillil/.vscode-remote-containers/bin/fe719cd3e5825bf14e14182fddeb88ee8daf044f/node'
[12590 ms] 
[12591 ms] 
[12591 ms] Exit code 1
[12592 ms] Start: Run in host: test -x '/home/begillil/.vscode-server/bin/fe719cd3e5825bf14e14182fddeb88ee8daf044f/node'
[12596 ms] 
[12596 ms] 
[12597 ms] Start: Run in host: test -f '/home/begillil/.vscode-server/bin/fe719cd3e5825bf14e14182fddeb88ee8daf044f/node_modules/node-pty/package.json'
[12600 ms] 
[12601 ms] 
[12601 ms] Start: Run in host: test -f '/home/begillil/.vscode-remote-containers/dist/vscode-remote-containers-server-0.209.6.js'
[12604 ms] 
[12605 ms] 
[12607 ms] userEnvProbe: loginInteractiveShell (default)
[12608 ms] userEnvProbe shell: /bin/bash
[12747 ms] userEnvProbe PATHs:
Probe:     '/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/begillil/.dotnet/tools'
Container: None
[12750 ms] Start: Run in Host: C:\Path\To\docker.exe version --format {{.Server.APIVersion}}
[12756 ms] Host server: (node:29747) UnhandledPromiseRejectionWarning: Error: spawn C:\Path\To\docker.exe ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:269:19)
    at onErrorNT (internal/child_process.js:465:16)
    at processTicksAndRejections (internal/process/task_queues.js:80:21)
(Use `node --trace-warnings ...` to show where the warning was created)
(node:29747) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 1)
[12757 ms] Host server: (node:29747) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.
[12759 ms] Host server: (node:29747) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 1)
[12760 ms] spawn C:\Path\To\docker.exe ENOENT
[12762 ms] CLI host's PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/begillil/.dotnet/tools
[305448 ms] Start: Run in Host: C:\Path\To\docker.exe version --format {{.Server.APIVersion}}
[305460 ms] Host server: (node:29747) UnhandledPromiseRejectionWarning: Error: spawn C:\Path\To\docker.exe ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:269:19)
    at onErrorNT (internal/child_process.js:465:16)
    at processTicksAndRejections (internal/process/task_queues.js:80:21)
(node:29747) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 2)
[305467 ms] spawn C:\Path\To\docker.exe ENOENT
[305468 ms] CLI host's PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/begillil/.dotnet/tools
[305469 ms] Host server: (node:29747) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 2)
[337359 ms] Start: Run in Host: C:\Path\To\docker.exe version --format {{.Server.APIVersion}}
[337365 ms] Host server: (node:29747) UnhandledPromiseRejectionWarning: Error: spawn C:\Path\To\docker.exe ENOENT
    at Process.ChildProcess._handle.onexit (internal/child_process.js:269:19)
    at onErrorNT (internal/child_process.js:465:16)
    at processTicksAndRejections (internal/process/task_queues.js:80:21)
(node:29747) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 3)
[337368 ms] spawn C:\Path\To\docker.exe ENOENT
[337369 ms] CLI host's PATH: /usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/usr/games:/usr/local/games:/snap/bin:/home/begillil/.dotnet/tools
[337370 ms] Host server: (node:29747) PromiseRejectionHandledWarning: Promise rejection was handled asynchronously (rejection id: 3)

Steps to Reproduce:

1. Configure remote.containers.dockerPath to a custom path, e.g. C:\Path\To\docker.exe
2. Remote-SSH: Connect Current Window to Host and open a folder
3. Attempt to run Remote-Containers: Attach to Running Container...

Expected: It shows a list of containers on the remote machine to attach to
Actual: A prompt saying "Docker version 17.12.0 or later is required" (just to confirm, both the local docker.exe and the remote docker installation are both newer than version 17.12.0)

The same steps did work on version 1.62.

I saw that recently #2994 was completed and made available in version 1.63, which is awesome. I've wished it worked that way since I first tried to set up this kind of remote container over ssh configuration.

However, it seems when that change was introduced, nothing accounted for the fact that existing custom docker executable paths were not likely to be available on the remote machine. So it tries to execute docker from a path that doesn't exist on the remote machine and assumes docker must not be installed when that fails.

Also, I'll add that if you do follow the "Docker version required" prompt and install docker, it will install Docker Desktop locally, but the custom path is still configured, and still not available on the remote machine, so it will still fail the same way.

I was able to fix the problem for myself by setting remote.containers.dockerPath back to the default value of docker, but it took a bit of research to figure out that that was the problem in order to get to that point.