Bug: 261529166
Ignore failures when sending the flush signal. Some processes may have
exited after we run `adb shell ps` but before we could send the flush signal.
Test: Successful run of coverage metrics using acov-llvm (as documented in go/android-native-coverage-local-workflow
Change-Id: I2fc0f71bf5f6d810b4124e28d7dd69ebfc2579b3
Signed-off-by: Shaju Mathew <shaju@google.com>