Restore solrj-tests later

#### Issue Description

Right now, the test in the solrj module is preventing a successful build (could be due to a temp outage?), due to this error:

```

R] Failed to execute goal on project deeplearning4j-dataimport-solrj: Could not resolve dependencies for project org.deeplearning4j:deeplearning4j-dataimport-solrj:jar:1.0.0-SNAPSHOT: Failed to collect dependencies at org.apache.solr:solr-test-framework:jar:7.7.1 -> org.restlet.jee:org.restlet:jar:2.3.0: Failed to read artifact descriptor for org.restlet.jee:org.restlet:jar:2.3.0: Could not transfer artifact org.restlet.jee:org.restlet:pom:2.3.0 from/to maven-default-http-blocker (http://0.0.0.0/): Blocked mirror for repositories: [maven-restlet (http://maven.restlet.org, default, releases+snapshots), apache.snapshots (http://repository.apache.org/snapshots, default, disabled)] -> [Help 1]

2021-05-08T00:02:42.7430866Z org.apache.maven.lifecycle.LifecycleExecutionException: Failed to execute goal on project deeplearning4j-dataimport-solrj: Could not resolve dependencies for project org.deeplearning4j:deeplearning4j-dataimport-solrj:jar:1.0.0-SNAPSHOT: Failed to collect dependencies at or

```

We can restore the test at a later date, but for now it's been deleted.



Please describe our issue, along with:

- expected behavior

- encountered behavior



#### Version Information



Please indicate relevant versions, including, if relevant:



* Deeplearning4j version

* Platform information (OS, etc)

* CUDA version, if used

* NVIDIA driver version, if in use



#### Additional Information



Where applicable, please also provide:



* Full log or exception stack trace (ideally in a Gist: gist.github.com)

* pom.xml file or similar (also in a Gist)



#### Contributing



If you'd like to help us fix the issue by contributing some code, but would

like guidance or help in doing so, please mention it!

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