CDRIVER-2222 fix /TLS/handshake_stall test
CDRIVER-2222 fix /TLS/handshake_stall test

This fix applies to zSeries failures that were taking ~100ms to create
a TLS stream with OpenSSL. That time was spent in
SSL_CTX_set_default_verify_paths. To reduce this time, the test now
explicitly specifies a CA cert.

beingmeta/mongo-c-driver,rcsanchez97/mongo-c-driver,mongodb/mongo-c-driver,beingmeta/mongo-c-driver,rcsanchez97/mongo-c-driver,ajdavis/mongo-c-driver,beingmeta/mongo-c-driver,derickr/mongo-c-driver,derickr/mongo-c-driver,mongodb/mongo-c-driver,acmorrow/mongo-c-driver,acmorrow/mongo-c-driver,acmorrow/mongo-c-driver,remicollet/mongo-c-driver,ajdavis/mongo-c-driver,ajdavis/mongo-c-driver,jmikola/mongo-c-driver,beingmeta/mongo-c-driver,ajdavis/mongo-c-driver,mongodb/mongo-c-driver,acmorrow/mongo-c-driver,rcsanchez97/mongo-c-driver,jmikola/mongo-c-driver,jmikola/mongo-c-driver,beingmeta/mongo-c-driver,mongodb/mongo-c-driver,mongodb/mongo-c-driver,rcsanchez97/mongo-c-driver,acmorrow/mongo-c-driver,derickr/mongo-c-driver,remicollet/mongo-c-driver,acmorrow/mongo-c-driver,remicollet/mongo-c-driver,derickr/mongo-c-driver,beingmeta/mongo-c-driver,rcsanchez97/mongo-c-driver,acmorrow/mongo-c-driver,jmikola/mongo-c-driver,mongodb/mongo-c-driver,derickr/mongo-c-driver,derickr/mongo-c-driver,jmikola/mongo-c-driver,rcsanchez97/mongo-c-driver,ajdavis/mongo-c-driver,remicollet/mongo-c-driver,mongodb/mongo-c-driver,ajdavis/mongo-c-driver,ajdavis/mongo-c-driver,remicollet/mongo-c-driver,remicollet/mongo-c-driver,derickr/mongo-c-driver,beingmeta/mongo-c-driver,beingmeta/mongo-c-driver,jmikola/mongo-c-driver,remicollet/mongo-c-driver,rcsanchez97/mongo-c-driver,jmikola/mongo-c-driver