Make overrideDefaultExcludes line into 3 lines

for improved readability.

Manually clean up some hard-to-read XML code in
jenkins_jobs/modules/publishers.py that was trying to do a lot on one
line.

Change-Id: Ica0065aae6f2fbaf8755bd8b5d3dea8c7d5a9cb0
Merge "Make overrideDefaultExcludes line into 3 lines"