test: Fix CTS tests on user builds.

CTS tests on user builds fail, because the `sched/sched_process_fork`
event in not accessible (unlike on userdebug builds).

Let's use sched/sched_switch instead. The exact event doesn't matter, we
just need an event that can be successfully enabled.

History of the test:

* On android 12, the `PerfettoFtraceIntegrationTest` suite was happily
  included on CTS tests and was passing on user and userdebug build.
* We mistakenly removed suite from CTS on android 13 with
  https://r.android.com/1952222, but it was kept in
  `perfetto_integrationtests` (which were only run on **userdebug**).
* We added a new test to the suite in https://r.android.com/2027444.
* I readded the `PerfettoFtraceIntegrationTest` in
  https://r.android.com/2612391

Tested by running:

```
atest CtsPerfettoTestCases:PerfettoFtraceIntegrationTest#ReportFtraceFailuresInStats -- --abi arm64-v8a
```

on a user master build.

Bug: 288274277
(cherry picked from https://android-review.googlesource.com/q/commit:d04c69d715d45a75c9ccc44e527b8951570eed10)
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:11dc17dc6ad015caf8c3d208f318d5d6ec572a3e)
Merged-In: Ifea07f718bbbd4917170604c3470475811e48b3b
Change-Id: Ifea07f718bbbd4917170604c3470475811e48b3b