migrations: Remove noop realm filters operations.

We followed a same approach as in #22611 to mark migrations as noops. We
might eventually squash them.

Migration operations that only change the validators should be removed
as they are essentially noops that do not affect the database schema.

However, ./manage.py makemigration still generates a new migration for
validators change regardless. So we still have to keep one migration
that updates the validators to the latest state. We prefer to keep the
earliest one for this purpose.

Signed-off-by: Zixuan James Li <p359101898@gmail.com>

zerver/migrations/0094_realm_filter_url_validator.py

@@ -1,5 +1,4 @@
 # Generated by Django 1.11.2 on 2017-07-22 13:44
-import django.core.validators
 from django.db import migrations, models
 
 from zerver.models import filter_format_validator
@@ -15,8 +14,6 @@ class Migration(migrations.Migration):
         migrations.AlterField(
             model_name="realmfilter",
             name="url_format_string",
-            field=models.TextField(
-                validators=[django.core.validators.URLValidator(), filter_format_validator]
-            ),
+            field=models.TextField(validators=[filter_format_validator]),
         ),
     ]

zerver/migrations/0368_alter_realmfilter_url_format_string.py

@@ -1,8 +1,8 @@
 # Generated by Django 3.2.8 on 2021-10-20 23:42
 
-from django.db import migrations, models
+from typing import List
 
-from zerver.models import filter_format_validator
+from django.db import migrations
 
 
 class Migration(migrations.Migration):
@@ -11,10 +11,4 @@ class Migration(migrations.Migration):
         ("zerver", "0367_scimclient"),
     ]
 
-    operations = [
-        migrations.AlterField(
-            model_name="realmfilter",
-            name="url_format_string",
-            field=models.TextField(validators=[filter_format_validator]),
-        ),
-    ]
+    operations: List[migrations.operations.base.Operation] = []