do not log stream close error for EOF

[GavinFrazar]

This PR eliminates a fake error log when closing file session uploads.

I noticed that every time I disconnected from a database, I would see this in the agent logs:

2024-01-24T15:29:46-08:00 DEBU [DB:SERVIC] Stop receiving from client. db:teleport-postgres-eastus-database-access-060a97ea-3a57-4218-9be5-dba3f19ff2b5 from:client id:432037ec-3dd4-46b1-964f-a2c28fa9352e postgres/engine.go:351
2024-01-24T15:29:46-08:00 DEBU [DB:SERVIC] Client done. db:teleport-postgres-eastus-database-access-060a97ea-3a57-4218-9be5-dba3f19ff2b5 error:[<nil>] id:432037ec-3dd4-46b1-964f-a2c28fa9352e postgres/engine.go:186
2024-01-24T15:29:46-08:00 DEBU [DB:SERVIC] Server connection closed. db:teleport-postgres-eastus-database-access-060a97ea-3a57-4218-9be5-dba3f19ff2b5 from:server id:432037ec-3dd4-46b1-964f-a2c28fa9352e postgres/engine.go:441
2024-01-24T15:29:46-08:00 DEBU [DB:SERVIC] Stopped parsing messages from server. db:teleport-postgres-eastus-database-access-060a97ea-3a57-4218-9be5-dba3f19ff2b5 from:server id:432037ec-3dd4-46b1-964f-a2c28fa9352e parsed_total:15 postgres/engine.go:434
2024-01-24T15:29:46-08:00 DEBU [DB:SERVIC] Stopped receiving from server. Transferred 1299 bytes. db:teleport-postgres-eastus-database-access-060a97ea-3a57-4218-9be5-dba3f19ff2b5 from:server id:432037ec-3dd4-46b1-964f-a2c28fa9352e postgres/engine.go:466
2024-01-24T15:29:46-08:00 INFO [AUDIT]     db.session.end cluster_name:mars.internal code:TDB01I db_name:postgres db_origin:cloud db_protocol:postgres db_service:teleport-postgres-eastus-database-access-060a97ea-3a57-4218-9be5-dba3f19ff2b5 db_type:azure db_uri:teleport-postgres.postgres.database.azure.com:5432 db_user:database-access-group ei:2 event:db.session.end private_key_policy:none sid:432037ec-3dd4-46b1-964f-a2c28fa9352e time:2024-01-24T23:29:46.947Z uid:e75146ce-5085-43a8-a7f2-aaec13e57aef user:martian user_kind:1 with_mfa:009ef81b-f0df-48fa-a853-fe441a1555c1 events/emitter.go:278
2024-01-24T15:29:51-08:00 DEBU [UPLOAD]    Scanned 1 uploads, started 1, found 0 corrupted in /Users/gavin/code/dev/storage/mars/data/agent/log/upload/streaming/default. filesessions/fileasync.go:302
2024-01-24T15:29:51-08:00 DEBU [UPLOAD]    Failed to close stream. error:[
ERROR REPORT:
Original Error: *interceptors.RemoteError EOF
Stack Trace:
	github.com/gravitational/teleport/api/client/auditstreamer.go:87 github.com/gravitational/teleport/api/client.(*auditStreamer).Close
	github.com/gravitational/teleport/lib/events/filesessions/fileasync.go:517 github.com/gravitational/teleport/lib/events/filesessions.(*Uploader).upload.func2
	github.com/gravitational/teleport/lib/events/filesessions/fileasync.go:591 github.com/gravitational/teleport/lib/events/filesessions.(*Uploader).upload
	github.com/gravitational/teleport/lib/events/filesessions/fileasync.go:461 github.com/gravitational/teleport/lib/events/filesessions.(*Uploader).startUpload.func1
	runtime/asm_arm64.s:1197 runtime.goexit
User Message: EOF] filesessions/fileasync.go:519
2024-01-24T15:29:51-08:00 DEBU [UPLOAD]    Session upload completed. duration:13.650583ms session-id:432037ec-3dd4-46b1-964f-a2c28fa9352e filesessions/fileasync.go:470

Note the inconsistency between "failed to close stream" and "session upload completed".

In fact, what happened is that the upload completed and the upstream auth server closed the stream, but when we check the error returned from stream.Close(ctx), it's actually wrapped in a RemoteError wrapper created by the api client's grpc stream interceptor.

Fixed by using errors.Is instead, since RemoteError implements Unwrap() error.

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[GavinFrazar]

I guess RemoteError was only added in #36866

However, I will backport to v13/v14 anyway

[public-teleport-github-review-bot]

@GavinFrazar See the table below for backport results.

Branch	Result
branch/v13	Create PR
branch/v14	Create PR
branch/v15	Create PR