Reclone repo after 3 failed sgm runs by default

Created by: varsanojidan

Currently, recloning after sgm failures is disabled y default, and can be modified by setting the SRC_SGM_RETRIES env variable. This leads to situations by default where sgm will not reclone a repo even after several failed sgm runs, leaving repos in potentially corrupted states forever. I've set the default to 3 failed sgm runs before reclone, and the reclones can still be disabled by setting SRC_SGM_RETRIES to -1 if desired.

Test plan

Just a default value change, N/A.