Deprecate SessionAuthenticator identify option #807

Job	Run time
cs-stan / Coding Standard & Static Analysis	27s
testsuite / testsuite-linux (8.3, highest, false)	37s
testsuite / testsuite-linux (8.2, lowest, false)	34s
testsuite / testsuite-linux (8.5, highest, false)	1m 19s
testsuite / testsuite-linux (8.4, highest, false)	1m 29s
testsuite / testsuite-linux (8.2, highest, false)	39s
	5m 5s

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