RFR: 8281254: GCs with survivor spaces report Init > Max through MXBeans

[Aleksey Shipilev]

See the discussion in the bug. This realistically affects only Serial and Parallel. My first attempt was to push through `initial_size` to generations properly, but it is too intrusive to my liking. The current patch "just" caps the initial to max.

Additional testing:
 - [x] New regression test now passes on all GCs
 - [x] Linux x86_64 `hotspot:tier1`

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Commit messages:
 - Revert extensive changes
 - Fix Parallel too
 - Better fix
 - Fix

Changes: https://git.openjdk.java.net/jdk/pull/7341/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=7341&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281254
  Stats: 95 lines in 2 files changed: 94 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk/pull/7341.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/7341/head:pull/7341

PR: https://git.openjdk.java.net/jdk/pull/7341