If Grafana rotates the user's auth token during a request to the data
source proxy it will set the Set-Cookie header with new auth token in
response before proxying the request to the datasource.
Before this fix the Set-Cookie response header was cleared after the
proxied request was finished to make sure that proxied datasources
cannot affect cookies in users browsers. This had the consequence
of accidentally also clearing the new auth token set in Set-Cookie
header.
With this fix the original Set-Cookie value in response header is now
restored after the proxied datasource request is finished. The existing
logic of clearing Set-Cookie response header from proxied request
have been left intact.
Fixes#16757
e210725d3d