Clean up annotation writing in classfile api: remove the redundant `Util.Writable` interfaces.
------------- Commit messages: - 8336756: Improve ClassFile Annotation writing Changes: https://git.openjdk.org/jdk/pull/20635/files Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20635&range=00 Issue: https://bugs.openjdk.org/browse/JDK-8336756 Stats: 123 lines in 3 files changed: 24 ins; 76 del; 23 mod Patch: https://git.openjdk.org/jdk/pull/20635.diff Fetch: git fetch https://git.openjdk.org/jdk.git pull/20635/head:pull/20635 PR: https://git.openjdk.org/jdk/pull/20635
