refactor(bin): remove references to FIPS_mode_set

[lrstewart]

Release Summary:

Description of changes:

Hopefully last of the openssl-1.0.2-fips cleanup. FIPS_mode_set was only required for openssl-1.0.2-fips, not for awslc or openssl3.

Testing:

I verified with a search that the only remaining references to FIPS_mode_set are in the s2n_fips.c comment discussing past behavior.

s2nd when built with awslc-fips:

./build/bin/s2nd --enter-fips-mode localhost 8888
libcrypto: AWS-LC FIPS 2.0.17
s2nd entered FIPS mode

s2nd when built with openss-1.1.1:

./build/bin/s2nd --enter-fips-mode localhost 8888
libcrypto: OpenSSL 1.1.1x-dev  xx XXX xxxx
FIPS mode not enabled: libcrypto does not support FIPS

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