RFR: 8351194: Clean up Hotspot SA after 32-bit x86 removal [v5]

[Kerem Kat]

> Remove 32-bit x86 specific code from the HotSpot Serviceability Agent following the removal of 32-bit x86 support.
> 
> - Removed x86-specific implementations and ifdef blocks.
> - Renamed files with X86 in the name when they are also used from AMD64, e.g. `X86Frame` → `AMD64Frame`.
> - Cleaned up platform detection logic in `PlatformInfo`.
> - Updated documentation references.

Kerem Kat has updated the pull request incrementally with one additional commit since the last revision:

  Revert "run RotateLeftNode*IdealizationTests on amd64 too"
  
  This reverts commit 1011b304f7cb4d195efc9239acd7784053c67cc1.

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Changes:
  - all: https://git.openjdk.org/jdk/pull/27844/files
  - new: https://git.openjdk.org/jdk/pull/27844/files/f6387b57..25aecd07

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=27844&range=04
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=27844&range=03-04

  Stats: 2 lines in 2 files changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/27844.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27844/head:pull/27844

PR: https://git.openjdk.org/jdk/pull/27844