RFR: 1308: CSRBot only reacts to approved CSR if PR is touched

[Erik Joelsson]

When a CSR issue is approved, any associated PR is only updated once someone touches the PR. The CSRBot will not evaluate anything about a PR unless there is a change to the PR. Since a CSR issue update only happens in JBS, the CSRBot cannot be limited by PR updates, it needs to check Jira for changes.

This patch removes the use of the PullRequestUpdateCache to limit when the bot evaluates a PR. If this turns out to generate too much load on JBS, we will have to implement a limiter in some way, but I don't think it will be a big issue in practice.

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

Commit messages:
 - Remove dead code
 - SKARA-1308

Changes: https://git.openjdk.java.net/skara/pull/1274/files
 Webrev: https://webrevs.openjdk.java.net/?repo=skara&pr=1274&range=00
  Issue: https://bugs.openjdk.java.net/browse/SKARA-1308
  Stats: 7 lines in 1 file changed: 0 ins; 7 del; 0 mod
  Patch: https://git.openjdk.java.net/skara/pull/1274.diff
  Fetch: git fetch https://git.openjdk.java.net/skara pull/1274/head:pull/1274

PR: https://git.openjdk.java.net/skara/pull/1274