#853: wrap GitLab VCS failures

[GHX5T-SOL]

Closes #853.

This PR updates GitlabRepo to wrap GitLab API failures raised by issue reads, close attempts, and comment creation. It covers the GitLab response errors from the ticket plus common transport failures, and it replaces the typoed can' comment read-error text with operation-specific wrapper messages.

What changed:

• widen issue, close_issue, and add_comment rescue handling from only Gitlab::Error::NotFound to GitLab API errors plus common transport failures
• cover Faraday::Error, Net::OpenTimeout, Net::ReadTimeout, Errno::ECONNREFUSED, and SocketError in the shared GitLab issue-operation rescue list
• add focused regressions for forbidden, rate-limit, timeout, and Faraday connection failures

Validation:

• PICKS=1 bundle exec rake test TEST=test/test_gitlab.rb in Docker Ruby 3.3 with libmagic-dev, Maven, and default JRE: 5 tests, 15 assertions, 0 failures, 0 errors, 0 skips
• PICKS=1 bundle exec ruby -Itest test/test_gitlab.rb in Docker Ruby 3.3: 5 tests, 15 assertions, 0 failures, 0 errors, 0 skips
• bundle exec rubocop objects/vcs/gitlab.rb test/test_gitlab.rb: 2 files inspected, no offenses detected
• bundle exec rubocop: 89 files inspected, no offenses detected
• git diff --check
• gitleaks dir --no-banner --redact --log-level error .
• GitHub Actions for this PR passed: actionlint, bashate, codecov, copyrights, markdown-lint, pdd, rake test, reuse, shellcheck, typos, xcop, yamllint, and Codacy

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