Replace ThreadLocal cache with ThreadIdCache

[gregw]

Use a cache class that will work better with virtual threads.

This generalized the "Pool-lite" algorithm introduced in PR #11498 to provide a cache that can be used to fix #10568

[gregw]

@lorban @sbordet I have now also replaced usages of ThreadLocalRandom with ThreadIdCache.Random, so we will not leak Random instances when using virtual threads.

For non-cache usages of ThreadLocal, we should look at changing the frequent pattern:

    Object oldValue = threadLocal.get();
    try
    {
        threadLocal.set(newValue);
        // ...
    } 
    finally
    {
        threadLocal.set(oldValue);
    }

to be replaced with the pattern (probably with help of a utility method):

    Object oldValue = threadLocal.get();
    try
    {
        threadLocal.set(newValue);
        // ...
    } 
    finally
    {
        if (oldValue == null)
            threadLocal.remove();
       else
            threadLocal.set(oldValue);
    }

or maybe even (@lorban is this worth the extra if?)

    Object oldValue = threadLocal.get();
    try
    {
        threadLocal.set(newValue);
        // ...
    } 
    finally
    {
        if (oldValue == null && VirtualThreads.isVirtualThread())
            threadLocal.remove();
       else
            threadLocal.set(oldValue);
    }

thoughts?

[sbordet]

Prooooobably just the number of cores is right!

[gregw]

I have merged this to #11498, where is can be further reviewed.