runner: fix URL of resilient log

monitor app shows:

![monoring app showing /log url](/uploads/dbb22484f79ed1538a308c640d74c3dc/image.png)

but this URL can not be accessed:

![/log URL unauthorized](/uploads/cf74f2d8bb867123c39264d8f7d9de74/image.png)

The correct URL looks to be this:

![/share/private/log is OK](/uploads/4775d5d3841d8ffa68d67f2cf2b87b22/image.png)

See merge request nexedi/slapos!785