Fix Whitelabel favicon not working in all browsers (#16022)

* Delete obsolete Safari favicon

* Set the default favicon path to the existing icon

* Delete fallback png favicons

* Fix placeholder in related Cypress test

frontend/test/metabase/scenarios/admin/settings/whitelabel.cy.spec.js

@@ -238,7 +238,7 @@ describeWithToken("formatting > whitelabel", () => {
       cy.visit("/admin/settings/whitelabel");
 
       cy.log("Add favicon");
-      cy.findByPlaceholderText("frontend_client/favicon.ico").type(
+      cy.findByPlaceholderText("/app/assets/img/favicon.ico").type(
         "https://cdn.ecosia.org/assets/images/ico/favicon.ico",
       );
       cy.get("ul")

resources/frontend_client/index_template.html

@@ -8,11 +8,8 @@
     <meta name="apple-mobile-web-app-capable" content="yes" />
     <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
     <link rel="apple-touch-icon" sizes="180x180" href="/app/assets/img/apple-touch-icon.png">
-    <link rel="icon" type="image/png" sizes="32x32" href="/app/assets/img/favicon-32x32.png">
-    <link rel="icon" type="image/png" sizes="16x16" href="/app/assets/img/favicon-16x16.png">
+    <link rel="icon" href="{{{favicon}}}" />
     <link rel="manifest" href="/app/assets/img/site.webmanifest">
-    <link rel="mask-icon" href="/app/assets/img/safari-pinned-tab.svg" color="#62a8e6">
-    <link rel="shortcut icon" href="/app/assets/img/favicon.ico">
     <meta name="msapplication-TileColor" content="#2d89ef">
     <meta name="msapplication-config" content="/app/assets/img/browserconfig.xml">
     <meta name="theme-color" content="#ffffff">
@@ -20,8 +17,6 @@
     <meta name="base-href" content="{{{baseHref}}}" />
     <meta name="uri" content="{{{uri}}}" />
 
-    <link rel="icon" href="{{{favicon}}}" />
-
     {{{embedCode}}}
 
     <title>{{{applicationName}}}</title>

src/metabase/public_settings.clj

@@ -242,7 +242,7 @@
   (deferred-tru "The url or image that you want to use as the favicon.")
   :visibility :public
   :type       :string
-  :default    "frontend_client/favicon.ico")
+  :default    "/app/assets/img/favicon.ico")
 
 (defsetting enable-password-login
   (deferred-tru "Allow logging in by email and password.")