Set umask for SharedClassesAPI test for OSX

[Mesbah-Alam]

SharedClassesAPI test will set groupaccess to the shared cache file. But it failed to set the access because of the default umask setting on osx. So the umask needs to be changed.

Ref: eclipse-openj9/openj9#4375 (comment)

We should make the change in the test's playlist. This way the test itself can set the umask dynamically during runtime without having any external dependencies.

[Mesbah-Alam]

Related: adoptium/infrastructure#881 (comment)