fix: migrate ApeCloud MySQL binlog path on upgrade

[wallyxjh]

Summary

• inject a compatibility init container for existing ApeCloud MySQL workloads during component workload reconciliation
• migrate legacy /data/mysql/data/mysql-bin.* entries into /data/mysql/binlog/ before mysqld starts
• rewrite /data/mysql/binlog/mysql-bin.index to absolute paths and mark successful migration to avoid repeat rewrites

Why

ApeCloud MySQL clusters created by older KB/addon versions can keep real binlog files under /data/mysql/data/mysql-bin.*. Newer configuration points log-bin and log_bin_index at /data/mysql/binlog/mysql-bin. After upgrade or reconfigure, WeSQL can start from the new bootstrap mysql-bin.000001 index and fail recovery with consensus_init_last_index_of_term for recovery failed.

Safety

• runs only for existing workloads, not brand-new workloads
• targets ApeCloud MySQL by image/component signals and requires the /data/mysql data mount
• no-ops when the legacy index is absent, when the migration marker exists, or when the new index is already beyond bootstrap
• backs up old/new index files and only moves conflicting target binlogs

Verification

• go generate ./pkg/testutil/k8s/mocks/...
• go test ./controllers/apps -run 'TestInjectMySQLBinlogPathCompatInitContainer|TestMemberJoinEnabled|TestDetectPodsToMemberJoin'\n- git diff --check\n\nNote: direct push to labring/fix/v0.9.3 is blocked by repository rules, so this PR targets that branch.