Delete orphaned test_kaiju function

The kaiju functionality was removed from viral_ngs.metagenomics but
this test was left behind. The test fails with:
  AttributeError: module 'viral_ngs.metagenomics' has no attribute 'kaiju'

There is no parser_kaiju, no Kaiju class, and no kaiju module anywhere
in the codebase - this test was testing dead code.

Author: dpark01

tests/unit/classify/test_metagenomics.py

@@ -273,20 +273,6 @@ def test_krakenuniq(mocker):
     p.assert_called_with('db', ['input.bam'], num_threads=mock.ANY, filter_threshold=mock.ANY, out_reports=['output.report'], out_reads=['output.reads'])
 
 
-def test_kaiju():
-    with patch('viral_ngs.metagenomics.kaiju.Kaiju.classify') as p:
-        args = [
-            'input.bam',
-            'db.fmi',
-            'tax_db',
-            'output.report',
-            '--outReads', 'output.reads',
-        ]
-        args = metagenomics.parser_kaiju(argparse.ArgumentParser()).parse_args(args)
-        args.func_main(args)
-        p.assert_called_with('db.fmi', 'tax_db', 'input.bam', output_report='output.report', num_threads=mock.ANY, output_reads='output.reads')
-
-
 class TestBamFilter(TestCaseWithTmp):
     def test_bam_filter_simple(self):
         temp_dir = tempfile.gettempdir()