Archive `google-ai-haystack`, `google-vertex-haystack`. Point to `google-genai-haystack`.

[julian-risch]

We want users to use google-genai-haystack instead of google-ai-haystack and google-vertex-haystack. If we don't expect any future releases for the two older integrations, we should do the following:

1. Update README files of the by adding a deprecation note and point to google-genai-haystack.
2. Make a final release of the two integrations, for example the version can be x.y.z.post0 similar to the final Haystack 1.26.4.post0 release.
3. Mark the two integrations on pypi as archived.

In the end, the README pages on pypi should look similar to the following, with a reference to google-genai-haystack.