When it syncs AWS DNS with k8s cluster content (at `--interval`), external-dns submits two distinct Route53 API calls:
* to fetch available zones (eg. for tag based zones discovery, or when zones are created after exernal-dns started),
* to fetch relevant zones' resource records.
Each call taxes the Route53 APIs calls budget (5 API calls per second per AWS account/region hard limit), increasing the probability of being throttled.
Changing synchronization interval would mitigate those calls' impact, but at the cost of keeping stale records for a longer time.
For most practical uses cases, zones list aren't expected to change frequently.
Even less so when external-dns is provided an explicit, static zones set (`--zone-id-filter` rather than `--aws-zone-tags`).
Using a zones list cache halves the number of Route53 read API calls.
When faced with errors from cloud providers (like "Throttling: Rate exceeded"), it's not always easy to find what operation caused the failure, and what action was aborted, if any,
Let's make it easier to identify an error source (and affected object when possible) by providing more context (and by using easy to find error messages).
