RFR: 1824: /reviewers N should remove ready status for clean backports [v3]

[Zhao Song]

> Currently, If a user issues /reviewers command in a clean backport, the reviewers requirement will not be displayed in the pr body and it won't be an integration blocker.
> 
> In this patch, after user issued /reviewers command, the reviewrs check for clean backport will be enabled. And if the Reviewers check requirements in the jcheck conf are stricter than the user's requirements, the bot will enforce the stricter requirements

Zhao Song has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains four additional commits since the last revision:

 - Merge branch 'master' into SKARA-1824
 - Update bots/pr/src/main/java/org/openjdk/skara/bots/pr/ReviewersCommand.java
   
   Co-authored-by: Erik Joelsson <37597443+erikj79 at users.noreply.github.com>
 - fix a problem
 - SKARA-1824

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

Changes:
  - all: https://git.openjdk.org/skara/pull/1482/files
  - new: https://git.openjdk.org/skara/pull/1482/files/aac73813..b1723243

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=skara&pr=1482&range=02
 - incr: https://webrevs.openjdk.org/?repo=skara&pr=1482&range=01-02

  Stats: 158 lines in 11 files changed: 152 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/skara/pull/1482.diff
  Fetch: git fetch https://git.openjdk.org/skara pull/1482/head:pull/1482

PR: https://git.openjdk.org/skara/pull/1482