RFR: 8348278: Trim InitialRAMPercentage to improve startup in default modes

[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`

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/23262/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=23262&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348278
  Stats: 1 line in 1 file changed: 0 ins; 0 del; 1 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