Remove preview flag from Java 11. (#15351)

src/azure-cli/azure/cli/command_modules/appservice/resources/LinuxFunctionsStacks.json

@@ -265,7 +265,7 @@
                             "use32BitWorkerProcess": false,
                             "linuxFxVersion": "Java|11"
                         },
-                        "isPreview": true,
+                        "isPreview": false,
                         "isDeprecated": false,
                         "isHidden": false
                     }

src/azure-cli/azure/cli/command_modules/appservice/resources/WindowsFunctionsStacks.json

@@ -207,7 +207,7 @@
                             "javaVersion": "11",
                             "use32BitWorkerProcess": true
                         },
-                        "isPreview": true,
+                        "isPreview": false,
                         "isDeprecated": false,
                         "isHidden": false
                     }