Avoid autogenerated varchar_pattern_ops indices created when using db_index=True or unique=True

For the following model definition, django will create two varchar_pattern_ops indices (for a_field and another_field). varchar_pattern_ops indices are useful for LIKE queries, but sometimes you don't plan on using them.

from django.db import models

class Something(models.Model):
    a_field = models.CharField(unique=True)
    another_field = models.CharField(db_index=True)
    yet_another_field = models.CharField()

root@e812b0255180:/app# python manage.py makemigrations
Migrations for 'api':
  api/migrations/0002_something.py
    - Create model Something
root@e812b0255180:/app# python manage.py sqlmigrate api 0002_something
BEGIN;
--
-- Create model Something
--
CREATE TABLE "api_something" ("id" bigint NOT NULL PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY, "a_field" varchar NOT NULL UNIQUE, "another_field" varchar NOT NULL, "yet_another_field" varchar NOT NULL);
CREATE INDEX "api_something_a_field_6e82347c_like" ON "api_something" ("a_field" varchar_pattern_ops);
CREATE INDEX "api_something_another_field_dd6f5906" ON "api_something" ("another_field");
CREATE INDEX "api_something_another_field_dd6f5906_like" ON "api_something" ("another_field" varchar_pattern_ops);
COMMIT;

How can you avoid those autogenerated varchar_pattern_ops indices?. Use Meta constraints and indexes, as seen below:

from django.db import models

class Something(models.Model):
    a_field = models.CharField()
    another_field = models.CharField()
    yet_another_field = models.CharField()

    class Meta:
        constraints = (
            models.UniqueConstraint(fields=(a_field,) name="a_field_uniq")
        )
        indexes = (
            models.Index(fields=("another_field",)),
        )

root@e812b0255180:/app# python manage.py makemigrations
Migrations for 'api':
  api/migrations/0002_something_something_a_field_uniq.py
    - Create model Something
    - Create constraint a_field_uniq on model something
root@e812b0255180:/app# python manage.py sqlmigrate api 0002_something_something_a_field_uniq
BEGIN;
--
-- Create model Something
--
CREATE TABLE "api_something" ("id" bigint NOT NULL PRIMARY KEY GENERATED BY DEFAULT AS IDENTITY, "a_field" varchar NOT NULL, "another_field" varchar NOT NULL, "yet_another_field" varchar NOT NULL);
--
-- Create constraint a_field_uniq on model something
--
ALTER TABLE "api_something" ADD CONSTRAINT "a_field_uniq" UNIQUE ("a_field");
CREATE INDEX "api_somethi_another_a44b66_idx" ON "api_something" ("another_field");
COMMIT;