RFR: 8281268: Resolve duplication of test ClassTransformer class

[Alex Menkov]

The fix deletes ClassTransformer class from jdi, switches all the test to jdk.test.lib copy.

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Commit messages:
 - deleted ClassTransformer in jdi lib

Changes: https://git.openjdk.java.net/jdk/pull/8710/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8710&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8281268
  Stats: 169 lines in 4 files changed: 1 ins; 163 del; 5 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8710.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8710/head:pull/8710

PR: https://git.openjdk.java.net/jdk/pull/8710