Upgrade to stylelint 15 (#22944)

- Upgrade stylelint and plugin
- Change ruleset to a explicit one, with all deprecated rules removed
- Fix new issues detected by value validation

For `overflow: overlay` see
https://github.com/stylelint/stylelint/issues/6667

web_src/less/modules/tippy.less

@@ -25,7 +25,7 @@
 }
 
 .tippy-box[data-theme="menu"] {
-  background-color: none;
+  background-color: transparent;
   color: var(--color-tooltip-text);
 }