Update GhidraPreparer and GitHubUtils class. Update Ghidra setup() to provide manual instructions in case setup fails. Update GitHubUtils#getJson() to retry if connection resets. Bug: 338152662 Test: Place ghidra.zip at /tmp/tradefed_ghidra/ghidra.zip/ghidra.zip and run a Ghidra based CTS Change-Id: I59a444a1e29834a41954c83c3cce1ec99b6984f7