Fix parsing of nested generics in Groovy

[knutwannheden]

• Fixes: Groovy parser does not correctly handle variables with nested type parameters. #4702

[github-actions]

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• rewrite-groovy/src/test/java/org/openrewrite/groovy/tree/BinaryTest.java
  • lines 209-209
• rewrite-groovy/src/test/java/org/openrewrite/groovy/tree/ClassDeclarationTest.java
  • lines 297-297
  • lines 311-311
• rewrite-groovy/src/test/java/org/openrewrite/groovy/tree/CompilationUnitTest.java
  • lines 132-132
• rewrite-groovy/src/test/java/org/openrewrite/groovy/tree/MethodDeclarationTest.java
  • lines 189-189
• rewrite-groovy/src/test/java/org/openrewrite/groovy/tree/VariableDeclarationsTest.java
  • lines 197-197