[Discover] Discover Classic View Filter In/Out placement when truncate:maxHeight is set to 0 (#129942)

* Change global injected CSS for truncating height
* Optimize CSS code
* Add requiresPageReload for TRUNCATE_MAX_HEIGHT

src/plugins/discover/public/components/doc_table/_doc_table.scss

@@ -124,3 +124,7 @@
     }
   }
 }
+
+.dscTruncateByHeight {
+  display: inline-block;
+}

src/plugins/discover/public/utils/truncate_styles.ts

@@ -18,12 +18,19 @@ const TRUNCATE_GRADIENT_HEIGHT = 15;
 const globalThemeCache = createCache({ key: 'truncation' });
 
 const buildStylesheet = (maxHeight: number) => {
+  if (!maxHeight) {
+    return [
+      `
+    .dscTruncateByHeight {
+      max-height: none;
+    }`,
+    ];
+  }
   return [
     `
     .dscTruncateByHeight {
       overflow: hidden;
       max-height: ${maxHeight}px !important;
-      display: inline-block;
     }
     .dscTruncateByHeight:before {
       top: ${maxHeight - TRUNCATE_GRADIENT_HEIGHT}px;
@@ -32,18 +39,7 @@ const buildStylesheet = (maxHeight: number) => {
   ];
 };
 
-const flushThemedGlobals = () => {
-  globalThemeCache.sheet.flush();
-  globalThemeCache.inserted = {};
-  globalThemeCache.registered = {};
-};
-
 export const injectTruncateStyles = (maxHeight: number) => {
-  if (maxHeight <= 0) {
-    flushThemedGlobals();
-    return;
-  }
-
   const serialized = serializeStyles(buildStylesheet(maxHeight), cache.registered);
   if (!globalThemeCache.inserted[serialized.name]) {
     globalThemeCache.insert('', serialized, globalThemeCache.sheet, true);

src/plugins/discover/server/ui_settings.ts

@@ -286,5 +286,6 @@ export const getUiSettings: (docLinks: DocLinksServiceSetup) => Record<string, U
         'The maximum height that a cell in a table should occupy. Set to 0 to disable truncation.',
     }),
     schema: schema.number({ min: 0 }),
+    requiresPageReload: true,
   },
 });