Studio CI: tolerate transient runner crashes in the llama-server log collection step (#5925)

The 'Collect llama-server logs' diagnostic step copies llama-server stdout into
the workspace for debugging. On the Windows runners it intermittently dies with
exit code -1073741502 (0xC0000142, STATUS_DLL_INIT_FAILED) when spawning the
copy, which failed the whole Tool calling Tests job even though the tests had
already run.

It is a diagnostic-only step, so mark it continue-on-error in all three jobs, the
same treatment #5913 gave the artifact-upload steps. A transient log-collection
crash no longer turns a green job red.

Refs #5913.