[Fix #8096] Fix a false positive for Lint/SuppressedException

[koic]

Fixes #8096

This PR fixes a false positive for Lint/SuppressedException
when empty rescue block in defs.

% cat example.rb
def self.foo
rescue Foo
  # ok
end

% bundle exec rubocop --only Lint/SuppressedException
(snip)

Inspecting 1 file
W

Offenses:

example.rb:2:1: W: Lint/SuppressedException: Do not suppress exceptions.
rescue Foo
^^^^^^^^^^

1 file inspected, 1 offense detected

---

Before submitting the PR make sure the following are checked:

• Wrote good commit messages.
• Commit message starts with [Fix #issue-number] (if the related issue exists).
• Feature branch is up-to-date with master (if not - rebase it).
• Squashed related commits together.
• Added tests.
• Added an entry to the Changelog if the new code introduces user-observable changes. See changelog entry format.
• The PR relates to only one subject with a clear title and description in grammatically correct, complete sentences.
• Run bundle exec rake default. It executes all tests and RuboCop for itself, and generates the documentation.

[bbatsov]

Thanks!