change G:D:A test allocation_paths

This is an attempt to fix this error:

ERROR: Failed to create directory (/tmp/allocation_testing_2v2Wmv/test_volume_2_hibzxi6/testing//tmp/allocation_testing_2v2Wmv/test_volume_2_hibzxi6/allocation_lock_testing_1_pKhDg6d) with return value = '', and error:
Can't mkdir('/tmp/allocation_testing_2v2Wmv/test_volume_2_hibzxi6/testing'): File exists at /gscmnt/gc13001/info/model_data/apipe-ci/workspace/1-Genome-Perl-Tests/PERL_VERSION=5.10/PERL_VERSION/5.10/lib/perl/Genome/Sys.pm line 839
ERROR: Can't mkdir('/tmp/allocation_testing_2v2Wmv/test_volume_2_hibzxi6/testing'): File exists at /gscmnt/gc13001/info/model_data/apipe-ci/workspace/1-Genome-Perl-Tests/PERL_VERSION=5.10/PERL_VERSION/5.10/lib/perl/Genome/Sys.pm line 839

I could not reproduce the error, but this change should fix the odd,
nested path.