qa-tests: test Erigon on a 32GB memory machine (#12809)

This PR modifies the tip-tracking test to test Erigon on the chain tip
by limiting the ram usage to 32gb (previously 64gb).

The ram limitation was obtained via cgroups:
```
cgcreate -a runner_user:runner_user -g memory:constrained_res_32G -t runner_user:runner_user
cgset -r memory.max=32G constrained_res_32G
cgset -r memory.swap.max=max constrained_res_32G
```
One
[run](https://github.com/erigontech/erigon/actions/runs/11939412573/job/33279879839)
showed some difficulty holding the tip. It is not clear if this was a
coincidence.

.github/workflows/qa-constrained-tip-tracking.yml

@@ -44,7 +44,7 @@ jobs:
         set +e # Disable exit on error
         
         # Run Erigon under memory constraints, wait sync and check ability to maintain sync
-        cgexec -g memory:constrained_res_64G python3 $ERIGON_QA_PATH/test_system/qa-tests/tip-tracking/run_and_check_tip_tracking.py \
+        cgexec -g memory:constrained_res_32G python3 $ERIGON_QA_PATH/test_system/qa-tests/tip-tracking/run_and_check_tip_tracking.py \
           ${{ github.workspace }}/build/bin $ERIGON_TESTBED_DATA_DIR $TRACKING_TIME_SECONDS $TOTAL_TIME_SECONDS Erigon3 $CHAIN standard_node statistics
   
         # Capture monitoring script exit status