Add a new target that uses GODEBUG=fips140=only to run unit tests.
This target should use the FIPS=true flag in order to pass -tags=requirefips.

(cherry picked from commit 8e304bd68cb4e0fad1dfbef5cf0e6040ad3589f3)

Co-authored-by: Michel Laterman <82832767+michel-laterman@users.noreply.github.com>
Co-authored-by: michel-laterman <michel.laterman@elastic.co>