RFR: 2328: Ignore bot user's comment when determining the latest action time of a PR [v2]

[Zhao Song]

> PullRequestPrunerBot is responsible for closing PRs that have not been active for a certain time. However, it currently doesn't ignore comments from bot users when determining the latest action time of a PR.

Zhao Song has updated the pull request incrementally with one additional commit since the last revision:

  update

-------------

Changes:
  - all: https://git.openjdk.org/skara/pull/1687/files
  - new: https://git.openjdk.org/skara/pull/1687/files/bc145c9f..e189bbfc

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1687&range=01
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1687&range=00-01

  Stats: 51 lines in 4 files changed: 31 ins; 0 del; 20 mod
  Patch: https://git.openjdk.org/skara/pull/1687.diff
  Fetch: git fetch https://git.openjdk.org/skara.git pull/1687/head:pull/1687

PR: https://git.openjdk.org/skara/pull/1687