DatasetConfigStatic, make copies #1441

Job	Run time
test (3.7, 2.3.0, TEST=asr_gt)	43s
test (3.7, 2.3.0, TEST=asr_specaugment)	42s
test (3.7, 2.3.0, TEST=hello)	50s
test (3.7, 2.3.0, TEST=nn_array)	42s
test (3.7, 2.3.0, TEST=nn_attention)	49s
test (3.7, 2.3.0, TEST=nn_base)	42s
test (3.7, 2.3.0, TEST=nn_cond)	46s
test (3.7, 2.3.0, TEST=nn_conformer)	41s
test (3.7, 2.3.0, TEST=nn_const)	41s
test (3.7, 2.3.0, TEST=nn_container)	39s
test (3.7, 2.3.0, TEST=nn_conv)	46s
test (3.7, 2.3.0, TEST=nn_debug_eager_mode)	42s
test (3.7, 2.3.0, TEST=nn_encoder)	44s
test (3.7, 2.3.0, TEST=nn_generated_layers)	38s
test (3.7, 2.3.0, TEST=nn_loop)	46s
test (3.7, 2.3.0, TEST=nn_loss)	57s
test (3.7, 2.3.0, TEST=nn_masked_computation)	51s
test (3.7, 2.3.0, TEST=nn_math)	44s
test (3.7, 2.3.0, TEST=nn_normalization)	57s
test (3.7, 2.3.0, TEST=nn_rand)	48s
test (3.7, 2.3.0, TEST=nn_rec)	38s
test (3.7, 2.3.0, TEST=nn_transformer)	44s
test (3.7, 2.3.0, TEST=nn_utils)	39s
test (3.7, 2.3.0, RUN="time python3 -m tests.test_nn_transformer")	37s
test (RUN=tests/pycharm-inspect.py, 3.7, 2.3.0)	4m 52s
	22m 38s

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