Do a proper delete of gen protos and re-run with newest

[mkysel]

Regenerate MLS protos and update build script to properly delete generated files before re-run using find-based removal

• Replace recursive shell glob deletion in dev/gen/protos with a find -exec rm -f command targeting *.pb.go, *.pb.gw.go, and *.swagger.json under pkg/proto.
• Regenerate MLS database protos adding message ReaddInstallationsData with V1 and field readded_installations, updating oneof wrappers, indices, and deprecation comments in intents.pb.go; total messages increase from 21 to 23.
• Update message contents protos removing PlaintextEnvelope_V2_ReaddRequest from PlaintextEnvelope_V2 in content.pb.go.
• Update group metadata protos adding enum CONVERSATION_TYPE_ONESHOT and optional oneshot_message field in group_metadata.pb.go with import wiring to oneshot.proto.
• Update group mutable metadata protos removing commit_log_signer from GroupMutableMetadataV1 in group_mutable_metadata.pb.go.
• Remove out-of-band artifacts by deleting out_of_band.pb.go and out_of_band.swagger.json.

📍Where to Start

Start with the cleanup logic in dev/gen/protos, then review regenerated changes beginning at pkg/proto/mls/database/intents.pb.go to trace new messages and index adjustments.

---

Macroscope summarized 31bffc0.

[graphite-app]

How to use the Graphite Merge Queue

Add either label to this PR to merge it via the merge queue:

• Queue - adds this PR to the back of the merge queue
• Hotfix - for urgent hot fixes, skip the queue and merge this PR next

You must have a Graphite account in order to use the merge queue. Sign up using this link.

An organization admin has enabled the Graphite Merge Queue in this repository.

Please do not merge from GitHub as this will restart CI on PRs being processed by the merge queue.

[api-Hypernova]

Looks good!