Conformance: introduce @ConditionalOnScenario #520

Job	Run time
Client Conformance (initialize)	43s
Client Conformance (sse-retry)	46s
Auth Conformance (auth/basic-cimd)	50s
Server Conformance	55s
Client Conformance (tools_call)	44s
Auth Conformance (auth/scope-retry-limit)	55s
Auth Conformance (auth/metadata-default)	47s
Auth Conformance (auth/token-endpoint-auth-none)	50s
Auth Conformance (auth/metadata-var3)	45s
Auth Conformance (auth/scope-from-scopes-supported)	50s
Auth Conformance (auth/scope-omitted-when-undefined)	40s
Client Conformance (elicitation-sep1034-client-defaults)	50s
Auth Conformance (auth/token-endpoint-auth-basic)	44s
Auth Conformance (auth/scope-step-up)	46s
Auth Conformance (auth/metadata-var1)	51s
Auth Conformance (auth/pre-registration)	51s
Auth Conformance (auth/token-endpoint-auth-post)	49s
Auth Conformance (auth/scope-from-www-authenticate)	49s
Auth Conformance (auth/metadata-var2)	48s
	15m 13s

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