fix: ci: Make the scan-build CI job actually run the static analyzer

scan-build was a silent no-op: the native file pinned CC to a name ccc-analyzer never intercepts.  Run meson and ninja under scan-build with --use-cc, drop the native file and LTO, and gate on all default checkers via --status-bugs.

Merge branch '6165-scan-build-actually-run-analyzer' into 'main'

See merge request isc-projects/bind9!12298