fix(modules/aptpkg): fix missing default `index` keys in `_get_opts`
fix(modules/aptpkg): fix missing default `index` keys in `_get_opts`

Regression introduced in b42487f5c01c630bb692715cfc93db0c5c143e0f (#61760).

Fixes #62176.

saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt,saltstack/salt