Fix memory warnings

The "close to default" warning now ignores the stack size which is
usually the default size.

The memory wastage warning should take into account the case where
native memory is bounded above.

The wastage warning message wording is improved.

[#58971702]
Merge 58971702-fix-memory-warnings to master

[Completes #58971702]
Delete extraneous focus

[#58971702]
Merge 58971702-remove-focus to master

[Completes #58971702]
Merge branch 'master' of github.com:cloudfoundry/java-buildpack
Changes to comply with pull request comments