Container builds incompatible with podman

### What versions & operating system are you using?

wrangler 4.21.2

### Please provide a link to a minimal reproduction

https://github.com/cloudflare/templates/tree/main/containers-template

### Describe the Bug

When attempting to deploy a container with [podman](https://podman.io/) rather than Docker, it fails to build as podman does not have the `--provenance` flag.

It appears that the flag is set to false anyways (https://github.com/cloudflare/workers-sdk/blob/2bdc3bb0d0f0c13dd1290c1dd9ca07d2e3e80bb9/packages/containers-shared/src/build.ts#L17), so I wonder if either that flag can be dropped (I am not sure why it's set to false in the first place), or just drop it if podman is detected.

### Please provide any relevant error logs

```
Building image hello-containers:0d302a66
Error: unknown flag: --provenance
See 'podman build --help'
```

Start in packages/containers-shared/src/build.ts, especially the build configuration around the --provenance flag, and use the containers-template reproduction with Podman. Confirm the behavior against the reported error, then verify that container builds work with Podman while preserving the intended Docker behavior.

Written by the indexing model from the issue text.