[SYCL][GRAPH] fix infinite loop bug in tryReuseExistingAllocation

[lslusarczyk]

Bug introduced in #19049
The bug causes llama CLI hang on any prompt if llama is run with graphs. After the fix llama CLI works.

@reble , there is a gap in sycl graphs unittesting which do not covered this case. You may consider adding some full-app (like llama CLI) graphs functional tests, which could also easily catch such issues.

[lslusarczyk]

@reble , CI is all green, please review this one-line fix and approve if it is OK

[reble]

@lslusarczyk Thanks for spotting this. CI was green before. We should add a regression test.
@mmichel11 can you help with this?

[lslusarczyk]

@lslusarczyk Thanks for spotting this. CI was green before. We should add a regression test. @mmichel11 can you help with this?

Since this blocks graphs with llama (and probably all other non-trivial apps), could you add the regression test in a separate PR after this fix is merged?

[mmichel11]

@lslusarczyk Thanks for spotting this. CI was green before. We should add a regression test. @mmichel11 can you help with this?

Since this blocks graphs with llama (and probably all other non-trivial apps), could you add the regression test in a separate PR after this fix is merged?

I suggest we add a test now for completeness. I've produced the issue in a small reproducer and will work it into a graph unit test on Monday.

[mmichel11]

@lslusarczyk I opened a PR to your fork's PR branch with a regression test: lslusarczyk#1

[adamfidel]

LGTM. The CI failure is the same as referenced in #21097.

[adamfidel]

@intel/llvm-gatekeepers Please consider merging :)