[jdk21u-dev] RFR: 8325055: Rename Injector.h

[Goetz Lindenmaier]

I backport this to make later backorts clean.

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Commit messages:
 - Backport 6787c4c3dd11d4d8db8255e59a1d71b6ab03cebb

Changes: https://git.openjdk.org/jdk21u-dev/pull/1763/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=1763&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8325055
  Stats: 10 lines in 4 files changed: 0 ins; 0 del; 10 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/1763.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/1763/head:pull/1763

PR: https://git.openjdk.org/jdk21u-dev/pull/1763