PreCommit_Python2_PVR_Flink_Commit flaky

cc: angoenka

Logs: https://builds.apache.org/job/beam_PreCommit_Python2_PVR_Flink_Commit/1687/console

Error:
42assert_that/Group/GroupByKey/GroupByWindow.None/beam:env:external:v1:0:beam:metric:sampled_byte_size:v1 {PCOLLECTION=ref_PCollection_PCollection_27}: DistributionResult{sum=59, count=1, min=59, max=59}))19:44:02 [flink-runner-job-invoker] WARN org.apache.beam.runners.fnexecution.jobsubmission.InMemoryJobService - Failed to remove job staging directory for token {"sessionId":"job_b05dbc6c-00d8-4df1-9bf1-efdf35899fa6","basePath":"/tmp/flinktestdPbkyj"}: {}19:44:02 java.io.FileNotFoundException: /tmp/flinktestdPbkyj/job_b05dbc6c-00d8-4df1-9bf1-efdf35899fa6/MANIFEST (No such file or directory)19:44:02 at java.io.FileInputStream.open0(Native Method)19:44:02 at java.io.FileInputStream.open(FileInputStream.java:195)19:44:02 at java.io.FileInputStream.<init>(FileInputStream.java:138)19:44:02 at org.apache.beam.sdk.io.LocalFileSystem.open(LocalFileSystem.java:118)19:44:02 at org.apache.beam.sdk.io.LocalFileSystem.open(LocalFileSystem.java:82)19:44:02 at org.apache.beam.sdk.io.FileSystems.open(FileSystems.java:252)19:44:02 at org.apache.beam.runners.fnexecution.artifact.BeamFileSystemArtifactRetrievalService.loadManifest(BeamFileSystemArtifactRetrievalService.java:88)19:44:02 at org.apache.beam.runners.fnexecution.artifact.BeamFileSystemArtifactStagingService.removeArtifacts(BeamFileSystemArtifactStagingService.java:92)19:44:02 at org.apache.beam.runners.fnexecution.jobsubmission.JobServerDriver.lambda$createJobService$0(JobServerDriver.java:63)19:44:02 at org.apache.beam.runners.fnexecution.jobsubmission.InMemoryJobService.lambda$run$0(InMemoryJobService.java:201)19:44:02 at org.apache.beam.runners.fnexecution.jobsubmission.JobInvocation.setState(JobInvocation.java:241)19:44:02 at org.apache.beam.runners.fnexecution.jobsubmission.JobInvocation.access$200(JobInvocation.java:48)19:44:02 at org.apache.beam.runners.fnexecution.jobsubmission.JobInvocation$1.onSuccess(JobInvocation.java:110)19:44:02 at org.apache.beam.runners.fnexecution.jobsubmission.JobInvocation$1.onSuccess(JobInvocation.java:96)19:44:02 at org.apache.beam.vendor.guava.v26_0_jre.com.google.common.util.concurrent.Futures$CallbackListener.run(Futures.java:1058)19:44:02 at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1149)19:44:02 at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:624)19:44:02 at java.lang.Thread.run(Thread.java:748)19:44:02 INFO:apache_beam.runners.portability.portable_runner:Job state changed to DONE*19:44:02* .INFO:_main_:removing conf dir: /tmp/flinktest-confGy17Mj*19:44:02*