Apply 15s timeout to subscription limit tests #6155

Job	Run time
build-and-check	3m 17s
test-integration-packages/internal	1m 0s
test-integration-packages/billing	1m 24s
test-integration-packages/agent-runtime	46s
test-integration-web	44s
test-packages/agent-runtime	40s
test-integration-cli	44s
test-web	57s
test-integration-sdk	1m 21s
test-packages/billing	40s
test-cli	57s
test-common	50s
test-packages/internal	49s
test-sdk	45s
test-.agents	53s
test-integration-common	49s
	16m 36s

Provide feedback