LdSvmTrainer slow behaviour when loading from a remote database

[superichmann]

System Information (please complete the following information):

• OS & Version: Windows 10
• ML.NET Version: 4.0.0
• .NET Version: 9

Describe the bug
When using DatabaseLoader from a remote database, the loading time and overall running time is much longer then other trainers.
As well the memory does not fills up quickly in comparison to different trainers

To Reproduce
Run LdSvmTrainer on a large dataset with hundreds of columns and millions of rows, should leave memory footprint. but it just consumes more and more data from the network sql and not fills up the memory, also takes about 100 times longer then lgbm / ff.

Run a different trainer (lgbm/ff) on the same dataset and see the memory footprint.

Expected behavior
LdSvmTrainer shoud load the entire data onto memory, similar to other ml.net trainers and then work on them.