Enable sdpa backends for server export in export.py #2577

Job	Run time
test-advanced-any / linux-job	17m 54s
test-advanced-cpu / linux-job	17m 30s
test-evaluation-any / linux-job	17m 38s
test-distributed-cuda / linux-job	9m 34s
test-evaluation-cpu / linux-job	18m 39s
test-gguf-any / linux-job	17m 37s
test-gguf-cpu / linux-job	17m 53s
test-multimodal-any / linux-job	4m 19s
test-multimodal-cpu / linux-job	4m 18s
test-native-cpu / linux-job	7m 9s
test-quantization-any / linux-job	17m 26s
test-native-any / linux-job	7m 10s
test-quantization-cpu / linux-job	17m 48s
test-readme-cpu / linux-job	9m 32s
test-readme-any / linux-job	9m 44s
	3h 14m 11s

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