Clear statements and remove actions in Manage Jena models menu take too much time

[litvinovg]

Describe the bug Manage Jena models provides controls to remove and clear model statements controls. Using this controls could lead to excessive IO usage and time of execution depends on model size

To Reproduce Steps to reproduce the behavior:

Clear statements 1.Open ingest tools -> Manage Jena Models -> Configuration models

2. Create new model
3. Add attached sample data to the model sample-data.zip
4. Click clear statements, execution takes a lot of time

Remove model

1. Create new model
2. Add attached sample data to the model sample-data.zip
3. Click remove, execution takes a lot of time

Expected behavior Those actions shouldn't take more than a few seconds to execute.