RFR: 8355524: Only every second line in upgradeable files is being used

[Severin Gehwolf]

Please review this fix to [JDK-8353185](https://bugs.openjdk.org/browse/JDK-8353185). The reading logic for the config file would erroneously use `scanner.nextLine()` when the current line to be added is in `line`. `line` is not being added, but `scanner.nextLine()` unintentionally skipping lines. The config file has a change too. It moves the `tzdb.dat` line last so that the existing test verifies that the `cacerts` one isn't being skipped. This slipped through because `tzdb.dat` updates aren't automatically tested.

Testing:
- [ ] GHA
- [x] The test from [JDK-8353185](https://bugs.openjdk.org/browse/JDK-8353185), `UpgradeableFileCacertsTest.java` fails with the config file change only (without the product fix) and passes with the one-liner. Also some manual testing when both files have been upgraded.

Thoughts?

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Commit messages:
 - 8355524: Only every second line in upgradable files is being read

Changes: https://git.openjdk.org/jdk/pull/24855/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=24855&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8355524
  Stats: 3 lines in 2 files changed: 1 ins; 1 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/24855.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/24855/head:pull/24855

PR: https://git.openjdk.org/jdk/pull/24855