RFR: 8336465: C2: EA incorrectly/unnecessarily checks for clinits

[Aleksey Shipilev]

As shown in [JDK-8336103](https://bugs.openjdk.org/browse/JDK-8336103), EA code uses `is_initializer` where we expect to only check for constructors. This PR rewrites it appropriately. This nominally changes the EA behavior, but I do not think it would actually show up anywhere.

Additional testing:
 - [x] Linux AArch64 server fastdebug, all (includes Fuzzer and CTW tests), passed as part of JDK-8336103 testing

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Commit messages:
 - Fix

Changes: https://git.openjdk.org/jdk/pull/20190/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20190&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8336465
  Stats: 2 lines in 1 file changed: 0 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/20190.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20190/head:pull/20190

PR: https://git.openjdk.org/jdk/pull/20190