Remove superfluous case normalization logic in App/User (#1049)

The Laravel email column is a `varchar(255)` with a `utf8mb4_unicode_ci` collation[1] which is case-insensitive. No further case normalization is required, and doing so will slow down the search.

Also, `strtolower()` only converts ASCII alphabetic characters[2]. `mb_strtolower()` is required to convert non-ASCII character as well.

[1]: https://mariadb.com/docs/server/reference/data-types/string-data-types/character-sets/supported-character-sets-and-collations
[2]: https://www.php.net/manual/en/function.strtolower.php

Bug: T415640

Author: outdooracorn

app/Console/Commands/User/CheckUserEmailExist.php

@@ -16,7 +16,7 @@ public function handle(WikiUserEmailChecker $emailChecker): int {
         foreach ($emails as $email) {
             $found = false;
 
-            if (User::whereEmailInsensitive($email)->exists()) {
+            if (User::whereEmail($email)->exists()) {
                 $this->line("FOUND: {$email} in apidb.users");
                 $found = true;
             }

app/User.php

@@ -121,8 +121,4 @@ public function sendEmailVerificationNotification() {
     public function getEmailForVerification() {
         return $this->email;
     }
-
-    public function scopeWhereEmailInsensitive($query, string $email) {
-        return $query->whereRaw('LOWER(email) = ?', [strtolower($email)]);
-    }
 }

tests/Commands/User/CheckUserEmailExistTest.php

@@ -60,7 +60,7 @@ public function testCaseInsensitive() {
             'email' => 'Test@Example.com',
         ]);
 
-        $exists = User::whereEmailInsensitive('tEsT@eXaMpLe.CoM')->exists();
+        $exists = User::whereEmail('tEsT@eXaMpLe.CoM')->exists();
 
         $this->assertTrue($exists);
     }