Improve encapsulation of weight_data_type_freq_ #10064

Job	Run time
Build Linux x64 Debug (ASan) / build_test_pipeline	32m 32s
Build Linux x64 Release / build_test_pipeline	34m 2s
Build Linux x64 Release with training / build_test_pipeline	37m 54s
Build Linux arm64 Debug / build_test_pipeline	52m 12s
Build Linux arm64 Release / build_test_pipeline	36m 11s
	3h 12m 51s

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