Remove extra newline at the end of HS descriptor

The rend-spec.txt document doesn't specify this extra newline. Furthermore,
this is the only descryptor type that contains one. Client and HSDir without
this patch still work perfectly since the HS descriptor parsing doesn't
expect a newline at the end.

Fixes #15296

Signed-off-by: David Goulet <dgoulet@ev0ke.net>

src/or/rendcommon.c

@@ -646,7 +646,6 @@ rend_encode_v2_descriptors(smartlist_t *descs_out,
         rend_encoded_v2_service_descriptor_free(enc);
         goto err;
     }
-    desc_str[written++] = '\n';
     desc_str[written++] = 0;
     /* Check if we can parse our own descriptor. */
     if (!rend_desc_v2_is_parsable(enc)) {