RFR: 8306658: GHA: MSVC installation could be optional since it might already be pre-installed [v3]

[Christoph Langer]

> We figured that seemingly the correct toolchain could be (and is) already installed by default on Github runners and it makes sense to skip the expensive installation operation which takes some 10+ minutes.
> 
> I also tested the scenario with an older toolchain version which would really need installing, e.g. 14.28.

Christoph Langer 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 four additional commits since the last revision:

 - Add review suggestions
 - Merge branch 'master' into ghastuff
 - JDK-8306658
   
   GHA: MSVC installation could be optional since it might already be pre-installed
 - JDK-8306543
   
   The installation error is probably caused by wrong wrong notation of path for --installPath option

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Changes:
  - all: https://git.openjdk.org/jdk/pull/13574/files
  - new: https://git.openjdk.org/jdk/pull/13574/files/2cb14408..d4d05751

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=13574&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=13574&range=01-02

  Stats: 2481 lines in 40 files changed: 2333 ins; 98 del; 50 mod
  Patch: https://git.openjdk.org/jdk/pull/13574.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/13574/head:pull/13574

PR: https://git.openjdk.org/jdk/pull/13574