[nominatim] Make failedJobsHistoryLimit configurable

[MatthiasLohr]

Hi @robjuz,

thanks for creating this helm chart!

Currently, I'm running into issues with long-running imports. I really would like to check the logs after the init job has failed, but unfortunately, the Pod is always deleted after it failed. Could you please make `failedJobsHistoryLimit' configurable? This way, the Pod is kept after is has failed and I can check the logs.

I'm sure this can also help others to debug import/init problems.

Thanks a lot!!!

Best regards
Matthias