fix(replication): surface HTTP 413 via paused/error events

[Mayankaggarwal8055]

Fixes #9165

HTTP 413 (Content Too Large) from CouchDB _bulk_docs during live replication was silently retried via backOff() instead of surfacing through paused(err) events as users expect.

Solution: In completeReplication(), treat 413 as fatal - emit paused(error) + error(error) and stop retrying.

Changes:

+ } else if (fatalError.status === 413) {
+   returnValue.emit('paused', fatalError);
+   returnValue.emit('error', fatalError);
+   returnValue.removeAllListeners();
+ } else {
    backOff(opts, returnValue, fatalError, function () {
      replicate(src, target, opts, returnValue);
    });