RFR: 8337027: Parallel: Obsolete BaseFootPrintEstimate

[Albert Mingkun Yang]

Simple obsoleting a Parallel GC product flag.

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

Commit messages:
 - pgc-obsolete-base-footprint

Changes: https://git.openjdk.org/jdk/pull/20299/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20299&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8337027
  Stats: 28 lines in 7 files changed: 0 ins; 25 del; 3 mod
  Patch: https://git.openjdk.org/jdk/pull/20299.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20299/head:pull/20299

PR: https://git.openjdk.org/jdk/pull/20299