RFR: 8348278: Trim InitialRAMPercentage to improve startup in default modes [v3]

[Aleksey Shipilev]

> See bug for discussion. This is the code change, which is simple. What is not simple is deciding what the new value should be. The change would probably require CSR, which I can file after we agree on the value.
> 
> I think cutting to 0.2% of RAM size gets us into good sweet spot:
>  - On huge 1024G machine, this yields 2G initial heap
>  - On reasonably sized 128G machine, this gives 256M initial heap
>  - On smaller 1G container, this gives 2M initial heap
> 
> Additional testing:
>  - [x] Linux AArch64 server fastdebug, `all`

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 four additional commits since the last revision:

 - Merge branch 'master' into JDK-8348278-trim-iramp
 - Also man page
 - Merge branch 'master' into JDK-8348278-trim-iramp
 - Fix

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/23262/files
  - new: https://git.openjdk.org/jdk/pull/23262/files/d3a327ae..6a6c3ab8

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=23262&range=02
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=23262&range=01-02

  Stats: 152480 lines in 3423 files changed: 68119 ins; 65042 del; 19319 mod
  Patch: https://git.openjdk.org/jdk/pull/23262.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/23262/head:pull/23262

PR: https://git.openjdk.org/jdk/pull/23262