Fix warnings that come up during deployment

Before we upgrade to the next NixOS release 23.05 (see !423 (merged)) we should first fix the current problems.

From https://whetstone.private.storage/privatestorage/PrivateStorageio/-/jobs/21637 :

• warning: Notifiers are deprecated upstream and will be removed in Grafana 10. Use services.grafana.provision.alerting.contactPoints instead.
• warning: The option nix.maxJobs' defined in PrivateStorageio/morph/grid/production/storage001-hardware.nix' has been renamed to `nix.settings.max-jobs'.
• To make project.stack-nix for LeaseReport a fixed-output derivation but not materialized, set stack-sha256 to the output of the 'calculateMaterializedSha' script in 'passthru'. To materialize project.stack-nix for LeaseReport entirely, pass a writable path as the materialized argument and run the 'updateMaterialized' script in 'passthru'.
• WARNING: cleanSourceWith called on /nix/store/l74k6l0sw0dfqnykxxa9zazlbxkqdb8n-source without a name. Consider adding name = "l74k6l0sw0dfqnykxxa9zazlbxkqdb8n-source";
• building '/nix/store/lm8wsx244j18sck1pyavnqijhrw701mg-unit-zfs-sync-root.service.drv'... Adding rules for package /nix/store/657bz7ny624a57550y7fhvmxka3nn417-extra-hwdb-file substituteStream(): WARNING: pattern '"/sbin/modprobe' doesn't match anything in file '/nix/store/sc1midrsbq15x116ykv190qz8y0hdxk8-udev-rules/00-path.rules'
  • (repeated ~ 50 times)
• warning: collision between /nix/store/n9m10qyqhrkq3caydkw0frdk31zn97yr-rtl8723bs-firmware-2017-04-06-xz/lib/firmware/rtlwifi/rtl8723bs_nic.bin.xz' and /nix/store/p3qzfp4dq5f9p3ak9ypqi67y62zjpf4l-linux-firmware-20221109-xz/lib/firmware/rtlwifi/rtl8723bs_nic.bin.xz'
  • (repeated ~ 50 times)