[Doc] Docker image build instructions update

### Search before asking

- [X] I searched in the [issues](https://github.com/apache/pulsar/issues) and found nothing similar.

### What issue do you find in Pulsar docs?

The commands:

```bash
mvn clean install -DskipTests
mvn package -Pdocker,-main -am -pl docker/pulsar-all -DskipTests
```
failes due to the fact, that now tagging is done by the maven-docker-plugin. To build the image, the parameter needs to be set first.

### What is your suggestion?

Update the command to:

```bash
gitrev=$(git rev-parse HEAD | colrm 10)
mvn clean install -DskipTests -Dgit.commit.id.abbrev=${gitrev}
mvn package -Pdocker,-main -am -pl docker/pulsar-all -DskipTests -Dgit.commit.id.abbrev=${gitrev}
```

### Any reference?

_No response_

### Are you willing to submit a PR?

- [X] I'm willing to submit a PR!