anonymous usage statistics should be disabled by default

When we enabled istio.hardened, we started noticing these messages in the logs:

errors: Post \"https://stats.grafana.org/loki-usage-report\": dial tcp ...:443: connect: connection refused; 

As it turns out, the default configuration of loki sends anonymous usage statistics to stats.grafana.org. We should probably turn this off in the default configuration. Anonymous usage statistics can be disabled by setting these values:

loki:
  analytics:
    reporting_enabled: false

I'm not sure if this should be done here or in the bigbang repo, but it seemed most appropriate to open an issue here first.

Supporting information:

• https://github.com/grafana/loki/issues/6016#issuecomment-1151851084
• https://grafana.com/docs/loki/latest/configure/#analytics
• https://github.com/grafana/loki/pull/5865/files