V13: Fix routing with string parameter

[nikolajlauridsen]

Fixes routing when a string parameter is used

This was caused by #16218 not considering invalid candidates

Fixes #16332 and #16341

Teting:

Create a site with a URL with more than one segment I.E

• Root
  • Child
    • Grandchild

Add an attribute routed endpoint with a string I.E.:

[HttpGet("sitemap-{group}-xml")]
    public IActionResult AttributeRoute(string group)
    {
        _logger.LogInformation("Got request: {GroupValue}", group);
        return Ok();
    }

Ensure you can request both /child/grandchild and /sitemap-something-xml