RFR: 1709: Only fetch comments once in PullRequestWorkItem in pr bot

[Zhao Song]

On Tue, 6 Dec 2022 23:57:39 GMT, Erik Joelsson <erikj at openjdk.org> wrote:

> This patch provides a minor optimization for `PullRequestWorkItem` subclasses in the pr bot by avoiding re-fetching of pr.comments(). I initially started this patch with a much bigger optimization in mind, but it turned out to not work. I still think it worth applying the remaining patch since I've gone through the trouble of implementing it.

LGTM

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Marked as reviewed by zsong (Committer).

PR: https://git.openjdk.org/skara/pull/1437