Mark inspector-protocol/heap-profiler/heap-objects-tracking.js as slow

Logs [1] show that the test was aborted while still processing
data chunks. Marking it a slow to rule out general slowness
of heap profiling.

[1]: https://ci.chromium.org/ui/p/chromium/builders/ci/Mac12%20Tests/18119/test-results?q=ID%3Aninja%3A%2F%2F%3Ablink_web_tests%2Finspector-protocol%2Fheap-profiler%2Fheap-objects-tracking.js+V%3Abuilder%3DMac12%2520Tests+V%3Aos%3DMac-12+V%3Atest_suite%3Dblink_web_tests&sortby=&groupby=

Bug: 330365759
Change-Id: Ia8f59115078d2533ed4be1056981d1872611d85a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5380606
Commit-Queue: Alex Rudenko <alexrudenko@chromium.org>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
Cr-Commit-Position: refs/heads/main@{#1276099}