mutations for collection 0xff not received in filtered DCP stream

For some reason, when creating a DCP connection filtering collection w/ id 0xff, mutations are not sent to the client.

Repro steps:

1. Create bucket testBucket
2. Create scope myScope on testBucket
3. Create enough collections on testBucket.myScope to ensure collection id advances to 0x100
4. Import single element into each of collection w/ cid 0xfe, 0xff, 0x100
5. Open 3 dcp streams, filtering 0xfe, 0xff, 0x100 respectively
6. Observe mutation sent to streams filtering on 0xfe & 0x100, but not for 0xff.

see attached cbcollect_infos, after running the above (n_0 -> data, n_1 -> analytics)

Marking as blocker, as this is blocking Analytics blocker issue, MB-43283