bugfix: Fix a bug that caused output without specifying index name

[Karibash]

close #3420

Fixed a bug that caused empty index names to be output when executing the introspect command with auto-generated index names.
This fix is necessary because the specification of the index name is mandatory.

drizzle-orm/drizzle-orm/src/mysql-core/indexes.ts

Lines 102 to 108 in 55231b0

	export function index(name: string): IndexBuilderOn {
	return new IndexBuilderOn(name, false);
	}
	export function uniqueIndex(name: string): IndexBuilderOn {
	return new IndexBuilderOn(name, true);
	}

[AndriiSherman]

it was closed automatically, sorry. I guess you would need to change base branch to main and reopen it

[AndriiSherman]

cc @Karibash