fix: hide connectivity HTML quota if not supported

This also solves the problem with the fact that
it's not clear from the resulting HTML
that this error message is referring to quota and not something else.
See https://github.com/chatmail/core/pull/8130.

src/scheduler/connectivity.rs

@@ -418,7 +418,11 @@ impl Context {
             };
             match &quota.recent {
                 Err(e) => {
-                    ret += &escaper::encode_minimal(&e.to_string());
+                    // If not supported by the provider,
+                    // just skip the "quota" section.
+                    if !matches!(e, crate::quota::Error::NotSupportedByProvider) {
+                        ret += &escaper::encode_minimal(&e.to_string());
+                    }
                 }
                 Ok(quota) => {
                     if quota.is_empty() {