New: Don't forcibly retest indexers/download clients/connections on save if previously enabled

Fixes #448

(cherry picked from commit b2b1600ebe7f022a3248ea12b69553e2d51a3a7c)

src/Readarr.Api.V1/ProviderControllerBase.cs

@@ -76,8 +76,10 @@ namespace Readarr.Api.V1
         public ActionResult<TProviderResource> UpdateProvider(TProviderResource providerResource)
         {
             var providerDefinition = GetDefinition(providerResource, false);
+            var existingDefinition = _providerFactory.Get(providerDefinition.Id);
 
-            if (providerDefinition.Enable)
+            // Only test existing definitions if it was previously disabled
+            if (providerDefinition.Enable && !existingDefinition.Enable)
             {
                 Test(providerDefinition, false);
             }