DPM install tries to install an already installed sdk version

When specifying an sdk version that's already been installed (and in this case from a different repo in the same registry):
```
testing git:(main) ✗ dpm install
SDK version 3.5.2-snapshot.20260623.672.0.v8c5b83be is already installed
Error: europe-docker.pkg.dev/da-images/public/sdk-manifests/open-source:3.5.2-snapshot.20260623.672.0.v8c5b83be: not found
```
```
testing git:(main) ✗ DPM_REGISTRY=europe-docker.pkg.dev/da-images/public-all \
dpm install

SDK version 3.5.2-snapshot.20260623.672.0.v8c5b83be is already installed
Successfully installed SDK 3.5.2-snapshot.20260623.672.0.v8c5b83be
Error: project uses both opt-in Components and SDK bundle, but dpm does not allow usage of both simultaneously
```
Could be from the following code block:
```
func installSdk(ctx context.Context, cmd *cobra.Command, config *assistantconfig.Config, sdkVersion *semver.Version) error {
_, err := assistantconfig.GetInstalledSdkVersion(config, sdkVersion)
if err == nil {
cmd.Printf("SDK version %s is already installed\n", sdkVersion.String())
```

Start at installSdk and the assistantconfig.GetInstalledSdkVersion call shown in the issue, then reproduce dpm install with the default and DPM_REGISTRY values. Trace what happens after the SDK is reported as already installed. Done means an existing SDK version is handled without the not-found error or an invalid simultaneous SDK/components state.

Written by the indexing model from the issue text.