Shared class cache generation update

[theresa-m]

Issue or pull request number:
eclipse-openj9/openj9#20029

Overview:
Changes to the shared classes cache generation number
The format of classes that are stored in the shared classes cache is changed due to eclipse-openj9/openj9#20029. As a result, the shared cache generation number is changed, which causes the JVM to create a new shared classes cache, rather than re-creating or reusing an existing cache. To save space, all existing shared caches can be removed unless they are in use by an earlier release. For more information about deleting a shared classes cache, see -Xshareclasses option.

Release target:
Eclipse OpenJ9 0.49.0

Applies to the following JDK versions:
T
All

Applies to the following platforms:
All

For new command line options:
n/a