fix(service ping): log body size of reports (#10686)

# Which Problems Are Solved

The current service ping reports can run into body size limit errors and
there's no way of knowing how big the current size is.

# How the Problems Are Solved

Log the current size to have at least some insights and possibly change
bulk size.

# Additional Changes

None

# Additional Context

- noticed internally
- backport to v4.x

docs/docs/self-hosting/manage/service_ping.md

@@ -85,3 +85,12 @@ This defines how many attempts the Service Ping feature will make to send data t
 for a specific interval and report. If one report fails, it will be retried up to this number of times. 
 Other reports will still be handled in parallel and have their own retry count. This means if the base information 
 only succeeded after three attempts, the resource count still has five attempts to be sent. 
+
+### BulkSize
+
+Certain reports, like the resource counts, can generate a lot of data. To prevent sending too much data in one request,
+the data is split into smaller chunks. This setting defines the maximum number of items that will be
+sent in one request. If there are more items, they will be sent in multiple requests.
+
+The size of the request is limited by the maximum request size of the central endpoint.
+Each report will log its size before sending it, so you can adjust the bulk size if needed.