Remove phytoref #1349

Job	Run time
Choose nextflow versions to test against depending on target branch	1s
nf-test (latest-everything, test, docker)	27s
nf-test (latest-everything, test_single, docker)	28s
nf-test (latest-everything, test_fasta, docker)	24s
nf-test (latest-everything, test_failed, docker)	29s
nf-test (latest-everything, test_multi, docker)	39s
nf-test (latest-everything, test_reftaxcustom, docker)	26s
nf-test (latest-everything, test_qiimecustom, docker)	1m 2s
nf-test (latest-everything, test_doubleprimers, docker)	38s
nf-test (latest-everything, test_iontorrent, docker)	24s
nf-test (latest-everything, test_novaseq, docker)	27s
nf-test (latest-everything, test_pacbio_its, docker)	47s
nf-test (latest-everything, test_sintax, docker)	28s
nf-test (latest-everything, test_pplace, docker)	27s
	7m 7s

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