Elastic Cloud Enterprise 3.7.3

The following changes are included in this release.

Upgrade system clusters. ECE 3.7.3 upgrades system clusters. Logging and metrics and admin console clusters are upgraded from 7.17.22 → 7.17.24. Security cluster is upgraded from 8.13.4 → 8.15.1

Coordinating IC zone_count cannot be 2 for security-cluster template. Fixes an issue where security-deployment was not allowed to be scaled-up from the UI, citing incorrect error for the coordinating node’s zone count.