Increase memory limit for many-extensions test

[mocenas]

Summary

Increase memory limit for super-size/many-extensions test. Migration to @ConfigMapping makes the native compilation require a lot more memory - see quarkusio/quarkus#44216

Please select the relevant options.

• Bug fix (non-breaking change which fixes an issue)
• Dependency update
• Refactoring
• Backport
• New scenario (non-breaking change which adds functionality)
• This change requires a documentation update
• This change requires execution against OCP (use run tests phrase in comment)

Checklist:

• Methods and classes used in PR scenarios are meaningful
• Commits are well encapsulated and follow the best practices

[michalvavrik]

LGTM, as daily native build is flaky already, we can tweak it if that turns out to be too much. Thanks