RFR: 8304403: Remove unused methods in RangeCheckElimination::Bound

[Eric Nothum]

Removed 3 unused methods in RangeCheckElimination:

RangeCheckEliminator::Bound::set_lower
RangeCheckEliminator::Bound::set_upper
RangeCheckEliminator::Bound::add_constant

Testing passed after removal

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Commit messages:
 - 8304403: removed unused functions in RangeCheckElimination

Changes: https://git.openjdk.org/jdk/pull/14328/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=14328&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8304403
  Stats: 23 lines in 2 files changed: 0 ins; 23 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/14328.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/14328/head:pull/14328

PR: https://git.openjdk.org/jdk/pull/14328