Fix late screenshot

Because of these two recent changes:
1. Do 'SERIALIZE PERFETTO TRACE' before 'DUMPSYS CRITICAL'
   to avoid polluting perfetto traces (b/296650898).
2. Do some more expensive post-processing in 'SERIALIZE PERFETTO TRACE' (increased latency).

the screenshot was beeing taken too late:
1. 'SERIALIZE PERFETTO TRACE'
2. 'DUMPSYS CRITICAL'
3. Take screenshot (got here too late!)

This commit changes the order to hide the 'SERIALIZE PERFETTO TRACE' latency:
1. Launch async 'SERIALIZE PERFETTO TRACE'
2. 'DUMPSYS CRITICAL'
3. Take screenshot (get here without waiting perfetto serialization)
4. Wait 'SERIALIZE PERFETTO TRACE' completion

Fix: b/316110955
Test: atest dumpstate_test dumpstate_smoke_test com.android.os.bugreports.tests.BugreportManagerTest
Ignore-AOSP-First: depends on changes (surfaceflinger) that cannot go into AOSP
Change-Id: I343813929a537c601132dd15db5e2c4d3fbbdcb1