When resume the pipeline halted by 404 error, the client doesn't as expected.

[xdxxxdx]

Versions
ldes/ldi-orchestrator:2.6.0-SNAPSHOT

Describe the bug
Thanks to #605, when the client now faces 404 error, the pipeline is halted as expected.
But when the source LDES stream is recovered, manually resume the pipeline by API call, the pipeline doesn't continue consuming the LDES stream.

To Reproduce

1. ldes/ldi-orchestrator:2.6.0-SNAPSHOT is up and running with the following configuration

server:
  port: 8080

orchestrator:
  pipelines:
    - name: bear-b-pipeline-client
      description: "bear-b dataset client for configured VSDS server"
      input:
        name: Ldio:LdesClient
        config:
          urls: http://ldes-server:8080/bearb/timebased-50
          source-format: "text/turtle"
      outputs:
            - name: Ldio:ConsoleOut
              config:
                content-type: text/turtle

spring:
  codec:
    max-in-memory-size: 10MB
    
logging:
  level:
    root: INFO
    Ldio.Application: INFO
    Ldio:HttpIn: DEBUG
    Ldio:HttpOut: DEBUG

http://ldes-server:8080/bearb/timebased-50 is not available for moment => UPDATED status for pipeline 'bear-b-pipeline-client' to HALTED as expected
3.http://ldes-server:8080/bearb/timebased-50 is back online
4. Call API http://localhost:8082/admin/api/v1/pipeline/bear-b-pipeline-client/resume to resume the pipeline

Current behavior
In the trace of LDIO we can see the pipeline is recovered, but it doesn't restart to consume the LDES stream.

Expected behavior
The pipeline is recovered and continue consuming the stream http://ldes-server:8080/bearb/timebased-50.
If resuming the pipeline doesn't' resume the function, there is no need to resume it..

[jobulcke]

A little investigation shows that the task that is responsible for everything in the ExecutorService is considered finished after an exception is thrown, which is not the case when the client is paused manually. So a way to "restart" the process(es) responsible in the client in a clean way needs to be found and implemented