Change base retry delay to 5 sec

[aok-foss]

All signing methods perform 3 attempts to sign.

The retrying code looks like the intention is to start with a delay of 5 seconds and then increase the delay exponentially: 5s before attempt 2, 11.1s before attempt 3.
Because the increase happens before the first retry, the actual delay times are 11.1s before attempt 2 and 37.3s before attempt 3.

This change makes the actual behaviour match the assumed intention.