Listing backups fails if more than 255 backups are available

[lenaschoenburg]

Describe the bug

Trying to list all available backups will always fail without a useful error message.
The gateway distributes a list request to all brokers which then list all of their backups and try to respond with a BackupListResponse:

https://github.com/camunda/zeebe/blob/4854b6606a803926ed9cadabfc2edb4aede18cb4/protocol/src/main/resources/cluster-management-protocol.xml#L64-L76

The groupSizeEncoding is defined by us:

https://github.com/camunda/zeebe/blob/c861aac736376e1cc20aa558979c6d9c289b4a1f/protocol/src/main/resources/common-types.xml#L16-L19

It uses a unit8 to represent the number of entries. When trying to write a BackupListResponse with more than 255 entries, the encoder rejects it:

java.lang.IllegalArgumentException: count outside allowed range: count=774
	at io.camunda.zeebe.protocol.management.BackupListResponseEncoder$BackupsEncoder.wrap(BackupListResponseEncoder.java:137) ~[zeebe-protocol-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.protocol.management.BackupListResponseEncoder.backupsCount(BackupListResponseEncoder.java:114) ~[zeebe-protocol-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.protocol.impl.encoding.BackupListResponse.write(BackupListResponse.java:100) ~[zeebe-protocol-impl-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.broker.transport.backupapi.BackupApiResponseWriter.write(BackupApiResponseWriter.java:71) ~[zeebe-broker-8.2.2.jar:8.2.2]
....

To Reproduce

Take 256 backups, then query all backups via GET actuator/backups.

Expected behavior

1. Zeebe supports much more backups than 255 (for example by using a uint16, thus supporting 65535 backups)
2. The number of listed backups should be limited to a reasonable number. Querying the backup store to list, say 1000, available backups is likely to result in timeouts and makes the backup API unusable.

Log/Stacktrace

Full Stacktrace

java.lang.IllegalArgumentException: count outside allowed range: count=774
	at io.camunda.zeebe.protocol.management.BackupListResponseEncoder$BackupsEncoder.wrap(BackupListResponseEncoder.java:137) ~[zeebe-protocol-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.protocol.management.BackupListResponseEncoder.backupsCount(BackupListResponseEncoder.java:114) ~[zeebe-protocol-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.protocol.impl.encoding.BackupListResponse.write(BackupListResponse.java:100) ~[zeebe-protocol-impl-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.broker.transport.backupapi.BackupApiResponseWriter.write(BackupApiResponseWriter.java:71) ~[zeebe-broker-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.transport.impl.ServerResponseImpl.write(ServerResponseImpl.java:50) ~[zeebe-transport-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.transport.impl.AtomixServerTransport.sendResponse(AtomixServerTransport.java:154) ~[zeebe-transport-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.broker.transport.backupapi.BackupApiResponseWriter.tryWriteResponse(BackupApiResponseWriter.java:51) ~[zeebe-broker-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.broker.transport.AsyncApiRequestHandler.lambda$handleRequest$1(AsyncApiRequestHandler.java:123) ~[zeebe-broker-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.scheduler.future.FutureContinuationRunnable.run(FutureContinuationRunnable.java:28) ~[zeebe-scheduler-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.scheduler.ActorJob.invoke(ActorJob.java:94) ~[zeebe-scheduler-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.scheduler.ActorJob.execute(ActorJob.java:45) [zeebe-scheduler-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.scheduler.ActorTask.execute(ActorTask.java:119) [zeebe-scheduler-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.scheduler.ActorThread.executeCurrentTask(ActorThread.java:106) [zeebe-scheduler-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.scheduler.ActorThread.doWork(ActorThread.java:87) [zeebe-scheduler-8.2.2.jar:8.2.2]
	at io.camunda.zeebe.scheduler.ActorThread.run(ActorThread.java:198) [zeebe-scheduler-8.2.2.jar:8.2.2]

Environment:

• Zeebe Version: >= 8.1