topdown/exported_tests: remove golang 1.16 x509 exception (#5032)
topdown/exported_tests: remove golang 1.16 x509 exception (#5032)

Forgotten cleanup when bumping the golang versions to 1.17/1.18/1.19.

Signed-off-by: Stephan Renatus <0d0a21c7604d0d452d5c1019ca18e48a97a9a057@gmail.com>
open-policy-agent/opa,open-policy-agent/opa,open-policy-agent/opa,open-policy-agent/opa,open-policy-agent/opa,open-policy-agent/opa