plugin-ldap: kill()/stop() not implemented on killable/pollable tasks

Sub-issue of kestra-io/kestra-ee#10964.

**Tasks:** io.kestra.plugin.ldap.Add, Modify, Delete, LdifToIon

**Why:** Unbounded while(true) loop reading/applying LDIF entries; no kill()/stop() for very large LDIF inputs. Lower priority: bounded by input size, no external resource left behind.

**Fix:** override `kill()` and/or `stop()` on these task classes to cancel the poll loop / close the consumer / cancel the remote job. See `io.kestra.plugin.gcp.bigquery.AbstractBigquery` for a reference implementation.

Start with io.kestra.plugin.ldap.Add, Modify, Delete, and LdifToIon, then compare their task lifecycle with io.kestra.plugin.gcp.bigquery.AbstractBigquery. Confirm how the unbounded LDIF poll loop is stopped, the consumer is closed, or a remote job is cancelled; done means the relevant kill()/stop() behavior is implemented for all four tasks.

Written by the indexing model from the issue text.