Revert "Enable the swift logs env vars for all jobs"

The zuul_swift_upload.py script doesn't work on centos. Revert
this commit to disable log uploading while we fix the script.

This reverts commit 63c57402838ed4c63c194c137dc4ea221e7b234d.

Change-Id: Ib2f29df4f9bd42de1e74f29f7f3e53ea2478e7ce