Migration will keep create and drop indexes if index name is the same across tables

[hkjeffchan]

Issue type:

[x] bug report

Database system/driver:

[x] mysql / mariadb

TypeORM version:

[x] latest

Steps to reproduce or a small repository showing the problem:
album.ts

@Entity('album')
@Index('album_id', ['id'])
export class Album {
    @Column('int', {
        nullable: false,
        primary: true,
        name: 'album_id',
    })
    id: number;
}

albumData.ts

@Entity('albumData')
@Index('album_id', ['id'])
export class AlbumData {
    @Column('int', {
        nullable: false,
        primary: true,
        name: 'album_id',
    })
    id: number;
}

This migration or schema sync will keep dropping and creating the index every time because the index columnNames are ['album_id', 'album_id'] and it should be ['album_id'] only.