Remove special HTTP HEAD processing

removing this allows HTTP 206 Partial Content responses and lets some clients(popcorn hour namely) play videos from JF.

Jellyfin.Api/Controllers/ImageController.cs

@@ -2020,12 +2020,6 @@ namespace Jellyfin.Api.Controllers
                 }
             }
 
-            // if the request is a head request, return a NoContent result with the same headers as it would with a GET request
-            if (isHeadRequest)
-            {
-                return NoContent();
-            }
-
             return PhysicalFile(imagePath, imageContentType ?? MediaTypeNames.Text.Plain);
         }
     }

Jellyfin.Api/Helpers/FileStreamResponseHelpers.cs

@@ -45,12 +45,6 @@ namespace Jellyfin.Api.Helpers
 
             httpContext.Response.Headers[HeaderNames.AcceptRanges] = "none";
 
-            if (isHeadRequest)
-            {
-                httpContext.Response.Headers[HeaderNames.ContentType] = contentType;
-                return new OkResult();
-            }
-
             return new FileStreamResult(await response.Content.ReadAsStreamAsync(cancellationToken).ConfigureAwait(false), contentType);
         }
 
@@ -70,12 +64,6 @@ namespace Jellyfin.Api.Helpers
         {
             httpContext.Response.ContentType = contentType;
 
-            // if the request is a head request, return an OkResult (200) with the same headers as it would with a GET request
-            if (isHeadRequest)
-            {
-                return new OkResult();
-            }
-
             return new PhysicalFileResult(path, contentType) { EnableRangeProcessing = true };
         }