tests: drop an extraneous (glob) from test-debugbackupbundle.t
Since this was not needed, it ends up causing the test to end with an error
saying that the output changed, but with no diff and a message at the end saying
"no result code from test".
Differential Revision: https://phab.mercurial-scm.org/D8269
% creating repo
% add and commit
C test.py
% change
M test.py