[TESTS] oauth2: make it possible to use an alternate http.Client

(cherry picked from commit aea4ab25a9)
(cherry picked from commit d386b212c4)
(cherry picked from commit c4935f08ad)
(cherry picked from commit dc6ca7cd25)
(cherry picked from commit 25296d5a3c)
(cherry picked from commit 3d54c64c5f)
(cherry picked from commit 6ece0b9d01)
(cherry picked from commit 3b39962033)
(cherry picked from commit 5e2167cd03)
(cherry picked from commit e676d7b265)
(cherry picked from commit 9cd258e865)
(cherry picked from commit 0a8d58c159)
(cherry picked from commit b66d06823a)
(cherry picked from commit 4fbe2a0047)
(cherry picked from commit a225e0c9b4)
(cherry picked from commit 21b670b927)
(cherry picked from commit d586e335d5)

services/auth/source/oauth2/providers_openid.go

@@ -43,6 +43,7 @@ func (o *OpenIDProvider) CreateGothProvider(providerName, callbackURL string, so
 	if err != nil {
 		log.Warn("Failed to create OpenID Connect Provider with name '%s' with url '%s': %v", providerName, source.OpenIDConnectAutoDiscoveryURL, err)
 	}
+	provider.HTTPClient = HTTPClient
 	return provider, err
 }