fapi: remove deprecated index function. #1654

Job	Run time
test-mbedtls (ubuntu-20.04)	4m 8s
test-mbedtls (ubuntu-22.04-mbedtls-3.1)	3m 49s
scanbuild	9m 2s
build-test (ubuntu-18.04, gcc)	8m 36s
build-test (ubuntu-18.04, clang)	7m 2s
build-test (ubuntu-20.04, gcc)	8m 50s
build-test (ubuntu-20.04, clang)	6m 33s
build-test (fedora-32, gcc)	8m 25s
build-test (fedora-32, clang)	9m 1s
build-test (opensuse-leap, gcc)	7m 26s
build-test (opensuse-leap, clang)	8m 25s
build-test (ubuntu-22.04, gcc)	9m 52s
build-test (ubuntu-22.04, clang)	8m 3s
build-test (alpine-3.15, gcc)	6m 4s
build-test (alpine-3.15, clang)	7m 18s
test-tcti-config	24m 29s
coverity-test	0s
test-coverage	8m 59s
test-fuzz	3m 29s
test-no-crypto-build	1m 33s
	2h 31m 4s

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