Remove unnecessary files about "Change Signature refactoring"

[CsCherrYY]

The PR is a follow-up of eclipse-jdt/eclipse.jdt.ui#428

[rgrunber]

I'm guessing the test failures are due to Java 20 support having been merged in the 4.28-I-builds ? So we probably need to do a release, then merge #2557 , and then we can merge this PR.

[fbricon]

test this please

[rgrunber]

Hold on, there's a small problem here. Most of the classes (not all) have a 2nd copy already! The differences I think are mostly whitespace related but we should verify. So I guess we're saving ~12k lines 😮

 100 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/rename/CuCollectingSearchRequestor.java
  98 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/CuCollectingSearchRequestor.java

 105 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/ExceptionInfo.java
 103 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/ExceptionInfo.java

  235 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/ParameterInfo.java
  232 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/ParameterInfo.java

  62 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/ReturnTypeInfo.java
  61 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/ReturnTypeInfo.java

  43 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/StubTypeContext.java
  42 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/StubTypeContext.java

  875 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/TypeContextChecker.java
  864 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/TypeContextChecker.java

  551 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/rename/RippleMethodFinder2.java
  539 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/rename/RippleMethodFinder2.java

  48 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/BodyUpdater.java
  48 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/structure/BodyUpdater.java

  3102 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/ChangeSignatureProcessor.java
  2914 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/structure/ChangeSignatureProcessor.java

  50 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/ls/core/internal/corext/refactoring/IDefaultValueAdvisor.java
  49 ./org.eclipse.jdt.ls.core/src/org/eclipse/jdt/internal/corext/refactoring/structure/IDefaultValueAdvisor.java

Update: Let me just verify that the classes being removed are all functionally identical to their duplicate.

Update 2: I've added a separate commit in the event that we discover some strange difference in behaviour, we can at least revert the part I introduced, since everything was fine before it. As far as I can tell, there isn't a difference though.

[rgrunber]

test this please.