Fix integration tests and docs for testing. #857

Job	Run time
Integration Test / Plan	5s
Integration Test / Build charm (wordpress-k8s)	2m 29s
Integration Test / Build rock (wordpress)	8m 9s
Integration Test / Plan Image Scanning	2s
Integration Test / Integration tests / Integration tests (test_addon)	22m 5s
Integration Test / Integration tests / Integration tests (test_core)	20m 37s
Integration Test / Integration tests / Integration tests (test_external)	17m 40s
Integration Test / Integration tests / Integration tests (test_ingress)	20m 27s
Integration Test / Integration tests / Integration tests (test_cos_grafana)	19m 43s
Integration Test / Integration tests / Integration tests (test_cos_loki)	17m 40s
Integration Test / Integration tests / Integration tests (test_cos_prometheus)	17m 42s
Integration Test / Scan Image (ghcr.io-canonical-wordpress-82efb77181a72470e40123f26350f191b28e3ee9-_1.0_amd64.tar)	1m 34s
Integration Test / Required Integration Test Status Checks	3s
	2h 28m 16s

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