Refactor lfs requests (#26783)

- Refactor lfs request code
- The original code uses `performRequest` function to create the
request, uses a callback to modify the request, and then send the
request.
- Now it's replaced with `createRequest` that only creates request and
`performRequest` that only sends the request.
- Reuse `createRequest` and `performRequest` in `http_client.go` and
`transferadapter.go`

---------

Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

modules/lfs/filesystem_client.go

@@ -15,7 +15,7 @@ import (
 
 // FilesystemClient is used to read LFS data from a filesystem path
 type FilesystemClient struct {
-	lfsdir string
+	lfsDir string
 }
 
 // BatchSize returns the preferred size of batchs to process
@@ -25,16 +25,12 @@ func (c *FilesystemClient) BatchSize() int {
 
 func newFilesystemClient(endpoint *url.URL) *FilesystemClient {
 	path, _ := util.FileURLToPath(endpoint)
-
-	lfsdir := filepath.Join(path, "lfs", "objects")
-
-	client := &FilesystemClient{lfsdir}
-
-	return client
+	lfsDir := filepath.Join(path, "lfs", "objects")
+	return &FilesystemClient{lfsDir}
 }
 
 func (c *FilesystemClient) objectPath(oid string) string {
-	return filepath.Join(c.lfsdir, oid[0:2], oid[2:4], oid)
+	return filepath.Join(c.lfsDir, oid[0:2], oid[2:4], oid)
 }
 
 // Download reads the specific LFS object from the target path