docs: describe containerset retrystrategy and verify it works. Fixes: #11502 #21017

Job	Run time
argoexec-image	35s
Get changed files	6s
Windows Unit Tests	9m 49s
Codegen	5m 3s
Lint	3m 52s
Unit Tests	4m 31s
E2E Tests (test-executor, minimal)	13m 58s
E2E Tests (test-corefunctional, minimal)	12m 49s
E2E Tests (test-functional, minimal)	20m 10s
UI	0s
E2E Tests (test-api, mysql)	7m 9s
E2E Tests (test-cli, mysql)	11m 35s
E2E Tests (test-cron, minimal)	6m 45s
E2E Tests (test-examples, minimal)	6m 8s
E2E Tests (test-plugins, plugins)	3m 48s
E2E Tests (test-java-sdk, minimal)	3m 44s
E2E Tests (test-python-sdk, minimal)	3m 9s
E2E Tests (test-executor, v1.25.11-k3s1, minimal)	13m 20s
E2E Tests (test-corefunctional, v1.25.11-k3s1, minimal)	13m 6s
E2E Tests (test-functional, v1.25.11-k3s1, minimal)	18m 14s
E2E Tests - Composite result	1s
	2h 37m 52s

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