Plugins: Fix colon in CallResource URL returning an error when creating plugin resource request (#79746)

* Plugin: handle colon character in path

url.Parse() does not handle the given input correctly when the input
contains a colon character. The user will see the following error
message when trying to use remote cluster in Elasticsearch:

```
level=warn msg="Failed for create plugin resource request" error="parse \"foo-*,*:foo-*/_mapping\": first path segment in URL cannot contain colon" traceID=
```

As far as I can tell, we only want to set the path here + rawquery so
avoid url.Parse() altogether.

* Add more tests

---------

Co-authored-by: Giuseppe Guerra <giuseppe@guerra.in>

pkg/api/plugin_resource.go

@@ -90,14 +90,11 @@ func (hs *HTTPServer) callPluginResourceWithDataSource(c *contextmodel.ReqContex
 func (hs *HTTPServer) pluginResourceRequest(c *contextmodel.ReqContext) (*http.Request, error) {
 	clonedReq := c.Req.Clone(c.Req.Context())
 	rawURL := web.Params(c.Req)["*"]
-	if clonedReq.URL.RawQuery != "" {
-		rawURL += "?" + clonedReq.URL.RawQuery
+
+	clonedReq.URL = &url.URL{
+		Path:     rawURL,
+		RawQuery: clonedReq.URL.RawQuery,
 	}
-	urlPath, err := url.Parse(rawURL)
-	if err != nil {
-		return nil, err
-	}
-	clonedReq.URL = urlPath
 
 	return clonedReq, nil
 }