[jfx20] RFR: 8302470: Change JBS version in .jcheck/conf to jfxNN[.0.MM]

[Kevin Rushforth]

In support of the JBS version change from "openjfxNN[.0.MM]" to "jfxNN[.0.MM]", we need to update the JBS version in .jcheck/conf in each active code line.

The planned cut-over date is Tuesday, Feb 28. I will integrate this PR immediately after the JBS version renaming is done.

NOTE: This PR is targeted to `jfx20`. I also created a separate PR targeted to `master`. This is a necessary exception to the usual rule where a fix goes into one or the other. In this case it needs to go into both so that they can be integrated immediately after the version change. The merge will have conflicts anyway, since the JBS fix versions are already different in the two branches, and doing it this way will allow a trivial resolution of the eventual merge conflict (which doesn't then have to be done urgently).

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Commit messages:
 - 8302470: Change JBS version in .jcheck/conf to jfxNN[.0.MM]

Changes: https://git.openjdk.org/jfx/pull/1034/files
 Webrev: https://webrevs.openjdk.org/?repo=jfx&pr=1034&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8302470
  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jfx/pull/1034.diff
  Fetch: git fetch https://git.openjdk.org/jfx pull/1034/head:pull/1034

PR: https://git.openjdk.org/jfx/pull/1034