Instead of selecting the base URL initially or when a load error occurs, it is now selected when a chunk or initialization chunk is created. The selected base URL is then assigned to `RepresentationHolder.lastUsedBaseUrl` that is excluded in case of a load error. For a next chunk another base URL will be selected by using the `BaseUrlExclusionList`.
#minor-release #exo-fixit
PiperOrigin-RevId: 395721221
