ci: perf tests always run on just 1 CPU

Author: triceo

run-coldstart.sh

@@ -1,4 +1,4 @@
 #!/bin/bash
 sudo -i sysctl kernel.perf_event_paranoid=1
 sudo -i sysctl kernel.kptr_restrict=0
-java -cp target/benchmarks.jar ai.timefold.solver.benchmarks.micro.coldstart.Main
+taskset -c 0 java -cp target/benchmarks.jar ai.timefold.solver.benchmarks.micro.coldstart.Main

run-scoredirector.sh

@@ -1,4 +1,4 @@
 #!/bin/bash
 sudo -i sysctl kernel.perf_event_paranoid=1
 sudo -i sysctl kernel.kptr_restrict=0
-java -cp target/benchmarks.jar ai.timefold.solver.benchmarks.micro.scoredirector.Main
+taskset -c 0 java -cp target/benchmarks.jar ai.timefold.solver.benchmarks.micro.scoredirector.Main