Revert "[clang] Add missing field to VisibilityAttr json AST dump"

This reverts commit 2107d87c.

Change is causing test failures on many bots:
- https://lab.llvm.org/buildbot/#/builders/164/builds/42180
- https://lab.llvm.org/buildbot/#/builders/188/builds/33880
- https://lab.llvm.org/buildbot/#/builders/245/builds/12558
- https://lab.llvm.org/buildbot/#/builders/258/builds/5404
- https://lab.llvm.org/buildbot/#/builders/249/builds/8049
- https://lab.llvm.org/buildbot/#/builders/230/builds/17170
- https://lab.llvm.org/buildbot/#/builders/91/builds/17108
- https://lab.llvm.org/buildbot/#/builders/109/builds/71264
- https://lab.llvm.org/buildbot/#/builders/139/builds/47461
- https://lab.llvm.org/buildbot/#/builders/216/builds/25598
- https://lab.llvm.org/buildbot/#/builders/36/builds/36549
- https://lab.llvm.org/buildbot/#/builders/247/builds/7747