Implement the ECKeyPairGenerator initialize func

Aim to solve openj9 issue 18320.
DefaultSignatureAlgorithm test run in those
Redhat OS based machines, FIPS version of
openssl is used in those machines. So, a 192
size of EC key pair generator is not allowed
by the native code in FIPS version of openssl
, then a Java implementation is used.

Remove 192-bits test.

test/jdk/sun/security/tools/keytool/fakegen/DefaultSignatureAlgorithm.java

@@ -60,7 +60,6 @@ public static void main(String[] args) throws Exception {
         check("DSA", 1024, null, "SHA256withDSA");
         check("DSA", 3072, null, "SHA256withDSA");
 
-        check("EC", 192, null, "SHA256withECDSA");
         check("EC", 384, null, "SHA384withECDSA");
         check("EC", 571, null, "SHA512withECDSA");