Remove session in api tests (#21984)

It's no meaning to request an API route with session.

tests/integration/api_httpsig_test.go

@@ -61,7 +61,7 @@ func TestHTTPSigPubKey(t *testing.T) {
 		Key:   keyType + " " + keyContent,
 	}
 	req := NewRequestWithJSON(t, "POST", keysURL, rawKeyBody)
-	session.MakeRequest(t, req, http.StatusCreated)
+	MakeRequest(t, req, http.StatusCreated)
 
 	// parse our private key and create the httpsig request
 	sshSigner, _ := ssh.ParsePrivateKey([]byte(httpsigPrivateKey))