feat(tools.func): use distro packages for MariaDB by default (#11049)

- Changed setup_mariadb() to use Debian/Ubuntu distribution packages by default
- Official MariaDB repository only used when specific version is requested
- Added cleanup logic for old/orphaned repository files with apt update
- Added version comparison to prevent downgrades (keeps higher version installed)
- Added automatic fallback to distro packages if repo installation fails
- Extracted _setup_mariadb_runtime_dir() helper function
- Updated all related documentation

This change improves reliability by avoiding MariaDB mirror issues
(HTTPS->HTTP redirects, geographic availability problems) for standard
installations while still allowing specific versions when needed.

docs/misc/tools.func/TOOLS_FUNC_USAGE_EXAMPLES.md

@@ -65,7 +65,7 @@ pkg_update
 
 setup_nginx
 setup_php "8.3"
-setup_mariadb "11"
+setup_mariadb  # Uses distribution packages (recommended)
 setup_composer
 
 msg_ok "Web stack installed"
@@ -388,7 +388,7 @@ pkg_install package-name
 # Chain multiple tools together
 setup_nodejs "20"
 setup_php "8.3"
-setup_mariadb "11"
+setup_mariadb  # Distribution packages (recommended)
 
 # Check command success
 if ! setup_docker; then