AbstractClassLoaderValue's 2 todos cleanup

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Hello,
When I am browsing, I find two TODOs in
jdk.internal.loader.AbstractClassLoaderValue
at
https://github.com/openjdk/jdk/blob/a6d950587bc68f81495660f59169b7f1970076e7/src/java.base/share/classes/jdk/internal/loader/AbstractClassLoaderValue.java#L137
and
https://github.com/openjdk/jdk/blob/a6d950587bc68f81495660f59169b7f1970076e7/src/java.base/share/classes/jdk/internal/loader/AbstractClassLoaderValue.java#L230

They can be changed into Thread.onSpinWait() calls. Mind create an issue on
jdk bug tracker?

Best regards