Revert "outposts/proxy: don't save raw jwt in cookie to prevent securecookie: the value is too long"

This reverts commit b3e40c6aed.

internal/outpost/proxyv2/application/oauth_callback.go

@@ -45,5 +45,6 @@ func (a *Application) redeemCallback(r *http.Request, shouldState string) (*Clai
 	if err := idToken.Claims(&claims); err != nil {
 		return nil, err
 	}
+	claims.RawToken = rawIDToken
 	return claims, nil
 }