ci(genai): Update `genai` directory to run tests in specific directories only #1239

Job	Run time
(legacy) Finding affected tests	16s
region tags	8s
lint	42s
(legacy) test (genai/tools)	52s
(legacy) test (genai/image-generation)	1m 17s
(legacy) test (genai/live)	37s
(legacy) test (genai/tuning)	27s
(legacy) test (genai/bounding-box)	41s
(legacy) test (genai/thinking)	54s
(legacy) test (genai/count-tokens)	43s
(legacy) test (genai/content-cache)	33s
(legacy) test (genai/controlled-generation)	40s
(legacy) test (genai/text-generation)	2m 44s
	10m 34s

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