Fix non-x64 bwc build targets

[andrross]

There were a few issues here: the '-x64' suffix was being unconditionally appeneded, debian uses underscores not hyphens, and the rpm target uses the '.86_64' suffix.

This feels like a hack, but the ./gradlew distribution:bwc:minor:buildBwc task now succeeds with this commit, whereas previously several of the targets failed. I've tested this on Intel Linux, Arm Linux, and Apple Silicon Mac. I think during a normal check run only the target that corresponds to the platform doing the building is executed, which is why the other targets were broken but no one had noticed. I'll happily entertain any suggestions on how to add a test for this!

Related Issues

Resolves #16535

Check List

• [x] Functionality includes testing.
• [ ] ~API changes companion pull request created, if applicable.~
• [ ] ~Public documentation issue/PR created, if applicable.~

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[github-actions[bot]]

:x: Gradle check result for 31baa412758038c0924e508135707364139ab909: FAILURE

Please examine the workflow log, locate, and copy-paste the failure(s) below, then iterate to green. Is the failure a flaky test unrelated to your change?

[github-actions[bot]]

:white_check_mark: Gradle check result for 31baa412758038c0924e508135707364139ab909: SUCCESS

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 0% with 6 lines in your changes missing coverage. Please review.

Project coverage is 72.08%. Comparing base (0363aa7) to head (31baa41). Report is 9 commits behind head on main.

Files with missing lines	Patch %	Lines
...e/internal/InternalDistributionBwcSetupPlugin.java	0.00%	6 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #16575 +/- ## ============================================ + Coverage 72.00% 72.08% +0.07% - Complexity 65038 65098 +60 ============================================ Files 5313 5314 +1 Lines 303454 303545 +91 Branches 43910 43923 +13 ============================================ + Hits 218510 218811 +301 + Misses 67040 66821 -219 - Partials 17904 17913 +9 ```

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