Plugin fails when running with maven using remote build cache

**Environment**:

- *Jib version:* 3.4.4
- *Build tool:* maven 3.9.9
- *OS:* linux/macos

**Description of the issue**:
when using the [maven remote build cache](https://maven.apache.org/extensions/maven-build-cache-extension/remote-cache.html), the plugin fails to build the jib, either failing with
```
Obtaining project build output files failed; make sure you have compiled your project before trying to build the image. (Did you accidentally run "mvn clean jib:build" instead of "mvn clean compile jib:build"?)
```

or when running using `packaged`
```
Failed to execute goal com.google.cloud.tools:jib-maven-plugin:3.4.4:dockerBuild (default) on project xxx: .../target/classes is not a directory
```

**Expected behavior**:
I understand that the plugin is relying on the compiled classes to exist when running in containerizingMode=exploded, but the packaged containerizingMode should (as far as i understood) use the existing jar file instead (which is the only thing existing when using a remote build cache)

**Steps to reproduce**:

1. setup a maven project with jib configured and maven build cache extension
2. run mvn clean package twice (second time for cache hit)
3. error

**`jib-maven-plugin` Configuration**:
```xml

com.google.cloud.tools
jib-maven-plugin

false

gcr.io/distroless/java21-debian12:nonroot

packaged


...



50051





package

dockerBuild




```

**Log output**:
```
Failed to execute goal com.google.cloud.tools:jib-maven-plugin:3.4.4:dockerBuild (default) on project xxx: .../target/classes is not a directory
```

**Additional Information**:
* when running maven using a remote cache build, there is no target/classes directory, but a `target/-.jar` file