RFR: 2552: Followup of SKARA-2408

[Zhao Song]

[SKARA-2408](https://bugs.openjdk.org/browse/SKARA-2408) is not working as expected since the first CheckWorkItem is processed before LabelerWorkItem. Therefore, the logic I added in [SKARA-2408](https://bugs.openjdk.org/browse/SKARA-2408) won't stop the bot from adding "rfr" label in the firstCheckWorkItem.

Currently, If a pr is not associated with any component, the bot will
1. Add "rfr" label in the first CheckWorkItem
2. Execute the LabelerWorkItem
3. In the next CheckWorkItem, it will remove the "rfr" label

This will cause a race between mlbridgeBot and prBot.

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Commit messages:
 - update
 - update
 - SKARA-2552

Changes: https://git.openjdk.org/skara/pull/1728/files
  Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1728&range=00
  Issue: https://bugs.openjdk.org/browse/SKARA-2552
  Stats: 35 lines in 5 files changed: 21 ins; 0 del; 14 mod
  Patch: https://git.openjdk.org/skara/pull/1728.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1728/head:pull/1728

PR: https://git.openjdk.org/skara/pull/1728