Improve pgo-build.sh (backport #351)

[mergify]

1. Reduce hard-coded path/version/etc, making it easier to maintain and use in both jdk11 and jdk21.
2. Add a step to configure jdk, so the script now works on fresh cloned repos.

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   This is an automatic backport of pull request Improve pgo-build.sh #351 done by Mergify.

[mergify]

Cherry-pick of 4037ffa has failed:

On branch mergify/bp/jdk-11/pr-351
Your branch is up to date with 'origin/jdk-11'.

You are currently cherry-picking commit 4037ffa.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   .github/scripts/pgo-build.sh

no changes added to commit (use "git add" and/or "git commit -a")

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[wks]

LGTM