Update docs for Java 25 and GKE migration (#3089)

Summarize all documentation updates across the repository to align with modern GKE, Cloud SQL Proxy v2, standard EPP fee v1.0, and Postgres database environments.

Key Updates:
- Prerequisites: Bump Java requirement to Java 25.
- Architecture & Scaling: Document GKE workloads, Cloud Tasks queues, and scheduled tasks. Replace App Engine references with GKE deployment restart commands (kubectl rollout restart).
- Configuration: Update Cloud SQL Proxy instructions to v2, fix keyring verification commands, and document IAP configuration.
- Escrow (RDE/BRDA): Fix manual generation and download procedures to match the Dataflow job ID folder structure, and correct deposit encryption/verification command parameters.
- Monitoring: Correct metric names and expand the documented metrics list with caching, locking, and reserved list metrics.
- Fixes: Standardize lists formatting across markdown files, fix broken webdriver links, and resolve various typos.
- Cleanup: Remove leftover cloud scheduler configurations for the deleted wipeOutContactHistoryPii task, and update ICANN reporting documentation to reflect open-sourced DNS query coordinator.

TAG=agy
CONV=88271e71-e272-40e0-85f8-a075a423b7c2

docs/proxy-setup.md

@@ -452,7 +452,7 @@ immediately after.
 ```bash
 $ gcloud container clusters create proxy-americas-cluster --enable-autorepair \
 --enable-autoupgrade --enable-autoscaling --max-nodes=3 --min-nodes=1 \
---zone=us-east1-c --cluster-version=1.9.4-gke.1 --tags=proxy-cluster \
+--zone=us-east1-c --tags=proxy-cluster \
 --service-account=<service-account-email>
 ```