WebUI

Fix Tiering config form descriptions and add missing reserve field #24525

Job	Run time
Checkout and Install	1m 18s
check-ux-team / Check UX Team Membership	4s
Run tests (UX Team - Self-hosted)	4m 28s
Build	2m 11s
Validate code style	4m 22s
Run tests (Standard)	0s
Collect coverage	17s
	12m 40s

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