Fix integration tests and docs for testing. #856

Job	Run time
Integration Test / Plan	8s
Integration Test / Build charm (wordpress-k8s)	4m 35s
Integration Test / Build rock (wordpress)	7m 49s
Integration Test / Plan Image Scanning	3s
Integration Test / Integration tests / Integration tests (test_addon)	46m 9s
Integration Test / Integration tests / Integration tests (test_core)	44m 59s
Integration Test / Integration tests / Integration tests (test_external)	44m 8s
Integration Test / Integration tests / Integration tests (test_ingress)	44m 20s
Integration Test / Integration tests / Integration tests (test_cos_grafana)	45m 13s
Integration Test / Integration tests / Integration tests (test_cos_loki)	44m 8s
Integration Test / Integration tests / Integration tests (test_cos_prometheus)	44m 32s
Integration Test / Scan Image (ghcr.io-canonical-wordpress-82efb77181a72470e40123f26350f191b28e3ee9-_1.0_amd64.tar)	1m 42s
Integration Test / Required Integration Test Status Checks	1s
	5h 27m 47s

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