sdk: Remove shortcut "publish-sdk", update PUBLISHING.md #5126

Job	Run time
build-and-check	2m 23s
test-integration-cli	39s
test-integration-packages/agent-runtime	37s
test-integration-backend	46s
test-integration-common	42s
test-integration-npm-app	46s
test-integration-.agents	1m 13s
test-integration-sdk	58s
test-integration-packages/internal	45s
test-.agents	41s
test-cli	1m 8s
test-backend	38s
test-web	40s
test-common	47s
test-packages/billing	45s
test-packages/agent-runtime	51s
test-integration-packages/billing	38s
test-sdk	1m 55s
test-packages/internal	44s
test-npm-app	40s
test-integration-web	40s
	18m 56s

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