Fix the way we generate random bytes for LTPA

[wrodrig]

In this change, we are looking to update the way we generate random bytes for LTPA keys and audit files. Using generateSeed() does not work for Hardware Crypto z/OS Systems and introduces the following error.

java.lang.UnsupportedOperationException com.ibm.ws.security.token.ltpa.internal.LTPAKeyCreateTask 

• I have considered the risk of behavior change or other zero migration impact (https://github.com/OpenLiberty/open-liberty/wiki/Behavior-Changes).
• If this PR fixes an Issue, the description includes "Fixes #FILLMEIN" or "Resolves #FILLMEIN" (verify release bug label if applicable: https://github.com/OpenLiberty/open-liberty/wiki/Open-Liberty-Conventions).
• If this PR resolves an external Known Issue (including APARS), the description includes "Fixes #FILLMEIN" or "Resolves #FILLMEIN".

[wrodrig]

!build
(view Open Liberty Personal Build - ❌ completed with errors/failures.)
spawn.fullfat.buckets=all

Note: Target locations of links might be accessible only to IBM employees.

[LibbyBot]

Code analysis and actions

DO NOT DELETE THIS COMMENT.

• 1 product code files were changed.
• Please describe in a separate comment how you tested your changes.