Let's use 2048 RSA keysize instead of 1024 in docs examples

We shall move to use 2048 bit keysize for generated RSA certificates in our examples in our WildFly documentation to avoid a warning that is generated by keytool distributed by JDKs in version 11+:

$ keytool -genkeypair -alias client -keyalg RSA -keysize 1024 -validity 365 -keystore client.keystore.jks -dname "CN=client" -keypass secret -storepass secret

Warning:
The generated certificate uses a 1024-bit RSA key which is considered a security risk and is disabled.

This change affects following two chapters in our WildFly documentation currently:

• https://docs.wildfly.org/24/WildFly_Elytron_Security.html#configure-ssltls
• https://docs.wildfly.org/24/WildFly_Elytron_Security.html#Web_Single_Sign_On