Java library lld issue: fix twice available count issue

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awesome-low-level-design/solutions/java/src/librarymanagementsystem/LibraryManagementSystem.java

Line 32 in 43017e5

copies.put(copyId, new BookCopy(copyId, item));

Issue: creating two BookCopy instances, each one adds itself to the LibraryItem copy list in its constructor.

Solution:
copies.put(copyId, copy); instead of copies.put(copyId, new BookCopy(copyId, item));