[code-reflection] RFR: Temporarily disable TestSmallCorpus tests

[Paul Sandoz]

Temporarily disable `TestSmallCorpus` tests until the stability improves when executing across image and explode builds.

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Commit messages:
 - Disable test

Changes: https://git.openjdk.org/babylon/pull/59/files
  Webrev: https://webrevs.openjdk.org/?repo=babylon&pr=59&range=00
  Stats: 2 lines in 1 file changed: 2 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/babylon/pull/59.diff
  Fetch: git fetch https://git.openjdk.org/babylon.git pull/59/head:pull/59

PR: https://git.openjdk.org/babylon/pull/59