fix rerun log file numbering; refs DE-556
fix rerun log file numbering; refs DE-556

test plan:
-Rerun logs at /usr/src/app/log/spec_failures/Rerun_ are ordered
properly starting with 1 and incrementing up by 1 for each rerun

Change-Id: I7b777eed1975cbea24a51602bef5b00fc8fd58f9
Reviewed-on: https://gerrit.instructure.com/c/canvas-lms/+/260317
Tested-by: Service Cloud Jenkins <9144042a601061f88f1e1d7a1753ea3e2972119d@instructure.com>
QA-Review: Kyle Rosenbaum <08c6582752644f4eca90309d6d9805aeb3128ceb@instructure.com>
Product-Review: Kyle Rosenbaum <08c6582752644f4eca90309d6d9805aeb3128ceb@instructure.com>
Reviewed-by: Aaron Ogata <11ccf682c06d1508642f943a3962a1c3d00b8e44@instructure.com>

instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms,sfu/canvas-lms,instructure/canvas-lms