fix(mysql): error 'backup retention should be > transaction log retention' on mysql replica

[diablo02000]

Description:

When creating Backup Cloud SQL, the predifined backup_retention_settings are the following

backup_configuration {
  backup_retention_settings {
    retained_backups = 7
    retention_unit   = "COUNT"
  }
}

Issue:

If transaction_log_retention_days is set to a value greater than the number of retained_backups, the following error occurs:

Error, failed to update instance settings for : googleapi: Error 400: Invalid request: backup retention should be > transaction log retention., invalid

Proposed Fix:

Update retained_backups value when transaction_log_retention_days is greater that predefined value (predefined: 7).

[imrannayer]

/gcbrun