Deprecate identifier collection approach. #676

Job	Run time
cs-stan / Coding Standard & Static Analysis	23s
testsuite / testsuite-linux (8.1, highest, false)	41s
testsuite / testsuite-linux (8.4, highest, false)	1m 15s
testsuite / testsuite-linux (8.3, highest, false)	30s
testsuite / testsuite-linux (8.2, highest, false)	30s
testsuite / testsuite-linux (8.1, lowest, false)	1m 3s
	4m 22s

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