telemetry(amazonq): add value for java downgrade attempt (#946)

## Problem

1) Two of the allowed values for the `codeTransformPreValidationError`
field were unused.
2) We need a way to represent when user tries to downgrade from 21->17
since that is not supported.

## Solution

Modify `allowedValues` accordingly.

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## License

By submitting this pull request, I confirm that my contribution is made
under the terms of the Apache 2.0 license.

Co-authored-by: David Hasani <[email protected]>

Author: dhasani23

telemetry/definitions/commonDefinitions.json

@@ -421,9 +421,8 @@
             "allowedValues": [
                 "NoPom",
                 "NoJavaProject",
-                "MixedLanguages",
                 "UnsupportedJavaVersion",
-                "ProjectJDKDiffersFromBuildSystemJDK",
+                "JavaDowngradeAttempt",
                 "UnsupportedBuildSystem",
                 "EmptyProject",
                 "NonSsoLogin",