RFR: 8357506: [JVMCI] Consolidate eager JVMCI initialization code

[Doug Simon]

While working on [JDK-8357135](https://bugs.openjdk.org/browse/JDK-8357135), I was reminded that some of the code implementing eager JVMCI compiler initialization (i.e. `-XX:+EagerJVMCI`) is in helper methods such as `JVMCIRuntime::call_getCompiler` that sound general purpose but are only used for eager JVMCI compiler initialization. This PR inlines `JVMCIRuntime::call_getCompiler` and renames `JVMCI::initialize_compiler` to `initialize_compiler_in_create_vm` to make its single use case clearer.

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Commit messages:
 - consolidate JVMCI eager initialization

Changes: https://git.openjdk.org/jdk/pull/25369/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=25369&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8357506
  Stats: 25 lines in 6 files changed: 5 ins; 14 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/25369.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/25369/head:pull/25369

PR: https://git.openjdk.org/jdk/pull/25369