Everywhere: Remove DeprecatedFlyString + any remaining references to it

Author: https://github.com/kennethmyhra
Commit: 3131e6369f
Pull-request: https://github.com/LadybirdBrowser/ladybird/pull/4153

AK/FlyString.cpp

@@ -4,7 +4,6 @@
  * SPDX-License-Identifier: BSD-2-Clause
  */
 
-#include <AK/DeprecatedFlyString.h>
 #include <AK/FlyString.h>
 #include <AK/HashTable.h>
 #include <AK/Singleton.h>
@@ -120,16 +119,6 @@ size_t FlyString::number_of_fly_strings()
     return all_fly_strings().size();
 }
 
-DeprecatedFlyString FlyString::to_deprecated_fly_string() const
-{
-    return DeprecatedFlyString(bytes_as_string_view());
-}
-
-ErrorOr<FlyString> FlyString::from_deprecated_fly_string(DeprecatedFlyString const& deprecated_fly_string)
-{
-    return FlyString::from_utf8(deprecated_fly_string.view());
-}
-
 unsigned Traits<FlyString>::hash(FlyString const& fly_string)
 {
     return fly_string.hash();