MDL-55372 stylelint: fully replace csslint

Remove the csslint config, remove an invalid property.

Kept csslint ignore lines becacase stylelint seems to respect them and
more work will be happening on css cleanup in MDL-55372.

.stylelintrc

@@ -50,6 +50,7 @@
         "media-feature-colon-space-after": "always",
         "media-feature-colon-space-before": "never",
         "media-feature-no-missing-punctuation": true,
+        "media-feature-parentheses-space-inside": "never",
         "media-feature-range-operator-space-after": "always",
         "media-feature-range-operator-space-before": "always",
         "media-query-list-comma-newline-after": "always-multi-line",
@@ -62,6 +63,7 @@
         "no-invalid-double-slash-comments": true,
         "no-unknown-animations": true,
         "property-case": "lower",
+        "property-no-unknown": true,
         "selector-attribute-brackets-space-inside": "never",
         "selector-attribute-operator-space-after": "never",
         "selector-attribute-operator-space-before": "never",

theme/bootstrapbase/less/moodle/responsive.less

@@ -75,7 +75,6 @@
         width: 100%;
         height: auto;
         max-height: 220px;
-        y-scroll: auto;
         float: none;
         border: 0px;
     }