RFR: 8365501: Remove speical AdapterHandlerEntry for abstract methods

[Ashutosh Mehra]

This PR removes the need for having AdapterHandlerEntry for abstract methods. The check for abstract method is now done in the accessor functions in Method such as Method::get_i2c_entry().
Motivation for this change is described in the JBS issue.

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Commit messages:
 - 8365501: Remove speical AdapterHandlerEntry for abstract methods

Changes: https://git.openjdk.org/jdk/pull/26764/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26764&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8365501
  Stats: 55 lines in 5 files changed: 11 ins; 38 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/26764.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26764/head:pull/26764

PR: https://git.openjdk.org/jdk/pull/26764