RFR: 1590: Convert PullRequestBot to use new poller [v2]

Fri Sep 16 17:02:15 UTC 2022

> With the new poller introduced in [SKARA-1565](https://bugs.openjdk.org/browse/SKARA-1565), we can now start converting more bots to use it. This issue covers the PullRequestBot. I'm posting the PR now already mostly to demonstrate of well the new poller fits in.

Erik Joelsson has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains two commits:

 - Merge branch 'SKARA-1565-pr-poll' into SKARA-1590-poller-pr-bot
 - SKARA-1590

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Changes: https://git.openjdk.org/skara/pull/1371/files
 Webrev: https://webrevs.openjdk.org/?repo=skara&pr=1371&range=01
  Stats: 37 lines in 1 file changed: 1 ins; 22 del; 14 mod
  Patch: https://git.openjdk.org/skara/pull/1371.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1371/head:pull/1371

PR: https://git.openjdk.org/skara/pull/1371