[FLINK-35489][Autoscaler] Ensure METASPACE size is computed before the heap

[ashangit]

What is the purpose of the change

If the heap usage with overhead leads to remaining memory to be assigned to the HEAP no memory will be assigned to the METASPACE leading to JVM failure at startup
By setting this before the HEAP we ensure the JVM can start with appropriate amount of METASPACE memory

Brief change log

(for example:)

• Compute METASPACE size to set before the HEAP size

Verifying this change

This change added tests and can be verified as follows:

• Extended tests to validate that despite a big HEAP usage that would lead to the whole memory being used by it, the METASPACE has been well set with all appropriate memory

Does this pull request potentially affect one of the following parts:

• Dependencies (does it add or upgrade a dependency): no
• The public API, i.e., is any changes to the CustomResourceDescriptors: no
• Core observer or reconciler logic that is regularly executed: yes

Documentation

• Does this pull request introduce a new feature? no
• If yes, how is the feature documented? not documented

[1996fanrui]

Thanks @ashangit for the detailed analysis and fix!

LGTM, and I hope to wait for @mxm 's double check before merging.

[mateczagany]

I think this makes sense and a good way to fix the original issue.

LGTM

[ashangit]

Updated the PR to take in account this comment in the jira ticket

[mxm]

Good fix @ashangit!

[1996fanrui]

Thanks @ashangit for the fix and everyone for the review!

Merging~