fix(ldap): convert default total GB to bytes when auto-creating clients (#5854)
* fix(ldap): convert default total GB to bytes when auto-creating clients
LdapSyncJob.buildClient stored ldapDefaultTotalGB directly into
Client.TotalGB without the GB-to-bytes conversion every other client
creation path applies (client form's gbToBytes, tgbot's
limitTraffic*1024^3, client_inbound_apply.go's totalGB*1024^3). A
"Default total (GB)" of 10 was persisted as 10 bytes, depleting the
client almost immediately.
Closes #5852
* test(ldap): pin the GB-to-bytes conversion in buildClient
Per review feedback on #5854: the existing test only exercised
defGB=0, so it wouldn't have caught the missing conversion.