RFR: 8313701: GHA: RISC-V should use the official repository for bootstrap [v2]

[Aleksey Shipilev]

> RISC-V is now the [official Debian architecture](https://lists.debian.org/debian-riscv/2023/07/msg00053.html). This means that the official repository is slowly building up the package set, while the old debian-ports repo is [slowly rotting](https://lists.debian.org/debian-riscv/2023/08/msg00007.html). For futureproof-ness, we want to bootstrap from the official repo going forward.
> 
> Additional testing:
>  - [x] GHA

Aleksey Shipilev has updated the pull request with a new target base due to a merge or a rebase. The incremental webrev excludes the unrelated changes brought in by the merge/rebase. The pull request contains two additional commits since the last revision:

 - Merge branch 'master' into JDK-8313701-riscv-gha
 - Fix

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/15149/files
  - new: https://git.openjdk.org/jdk/pull/15149/files/530c2932..395f0000

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=15149&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=15149&range=00-01

  Stats: 243 lines in 38 files changed: 109 ins; 16 del; 118 mod
  Patch: https://git.openjdk.org/jdk/pull/15149.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15149/head:pull/15149

PR: https://git.openjdk.org/jdk/pull/15149