[TESTS] update self signed certificate

[sehaas]

update self signed test certificate

• use 2048 bit RSA key
• use sha256 certificate hash
• CN=alpn tests,O=jetty project,OU=jetty alpn as certificate name

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We recently switched to the OpenJDK version provided by Fedora 28 (java-1.8.0-openjdk, 1:1.8.0.191.b12-8.fc28). With this version the tests kept failing (Maven logfile).

The Fedora version has the option security.useSystemPropertiesFile enabled which loads following config from /etc/crypto-policies/back-ends/java.config:

jdk.tls.ephemeralDHKeySize=1023
jdk.certpath.disabledAlgorithms=MD2, MD5, DSA, RSA keySize < 2048
jdk.tls.disabledAlgorithms=DH keySize < 1023, SSLv2, SSLv3, DHE_DSS, RSA_EXPORT, DHE_DSS_EXPORT, DHE_RSA_EXPORT, DH_DSS_EXPORT, DH_RSA_EXPORT, DH_anon, ECDH_anon, DH_RSA, DH_DSS, ECDH, 3DES_EDE_CBC, DES_CBC, RC4_40, RC4_128, DES40_CBC, RC2, HmacMD5
jdk.tls.legacyAlgorithms=

With this config the the old key (DSA) and cert (dsaWithSHA1) won't be used during the connection handshake. Updating the key and cert works on Oracle JDK and OpenJDK.

[sbordet]

@sehaas you did not sign-off your commit, see the contribution guidelines. Otherwise the PR is acceptable.

[sehaas]

@sbordet done.

[sbordet]

Thanks!