RFR: 8303250: Call ct_max_alignment_constraint using the base class

[Albert Mingkun Yang]

Trivial refactoring to use more precise class.

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Commit messages:
 - cardtable-static

Changes: https://git.openjdk.org/jdk/pull/12765/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=12765&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8303250
  Stats: 4 lines in 2 files changed: 0 ins; 0 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/12765.diff
  Fetch: git fetch https://git.openjdk.org/jdk pull/12765/head:pull/12765

PR: https://git.openjdk.org/jdk/pull/12765