[GOBBLIN-1505] Add metrics for WorkUnit count

[umustafi]

*Emitted in the form <flowgroup>.<flowname>.workunits

Dear Gobblin maintainers,

Please accept this PR. I understand that it will not be reviewed until I have checked off all the steps below!

JIRA

• My PR addresses the following Gobblin JIRA issues and references them in the PR title. For example, "[GOBBLIN-XXX] My Gobblin PR"
  • https://issues.apache.org/jira/browse/GOBBLIN-1505

Description

• Here are some details about my PR, including screenshots (if applicable):
  From a user/platform perspective, we want to see how many workunits are being created for each flow. The metric of workunit count will be emitted in the form ..workunits.

Tests

• My PR adds the following unit tests OR does not need testing for this extremely good reason:
  Tested with flows launched on gaas to see log statement "Reporting metrics for host: {}, app: {} to Ingraphs with reporting interval of {} seconds."

Commits

• My commits all reference JIRA issues in their subject lines, and I have squashed multiple commits if they address the same issue. In addition, my commits follow the guidelines from "How to write a good git commit message":
  1. Subject is separated from body by a blank line
  2. Subject is limited to 50 characters
  3. Subject does not end with a period
  4. Subject uses the imperative mood ("add", not "adding")
  5. Body wraps at 72 characters
  6. Body explains "what" and "why", not "how"

[codecov-commenter]

Codecov Report

Merging #3351 (a14fdb2) into master (de94515) will decrease coverage by 0.01%.
The diff coverage is 0.00%.

@@             Coverage Diff              @@
##             master    #3351      +/-   ##
============================================
- Coverage     46.43%   46.41%   -0.02%     
- Complexity    10120    10155      +35     
============================================
  Files          2052     2056       +4     
  Lines         79656    80102     +446     
  Branches       8896     8950      +54     
============================================
+ Hits          36991    37183     +192     
- Misses        39226    39472     +246     
- Partials       3439     3447       +8     

Impacted Files	Coverage Δ
...rg/apache/gobblin/runtime/AbstractJobLauncher.java	61.11% <ø> (-0.15%)	⬇️
...blin/service/monitoring/KafkaJobStatusMonitor.java	35.57% <0.00%> (-7.45%)	⬇️
...leshooter/InMemoryMultiContextIssueRepository.java	60.00% <0.00%> (-35.24%)	⬇️
...a/org/apache/gobblin/util/limiter/NoopLimiter.java	40.00% <0.00%> (-20.00%)	⬇️
...g/apache/gobblin/util/filters/RegexPathFilter.java	72.72% <0.00%> (-16.17%)	⬇️
...lin/util/filesystem/FileSystemInstrumentation.java	85.71% <0.00%> (-14.29%)	⬇️
...e/gobblin/runtime/local/LocalTaskStateTracker.java	72.97% <0.00%> (-7.59%)	⬇️
...t/version/TimestampedDatasetStateStoreVersion.java	27.77% <0.00%> (-5.56%)	⬇️
...in/java/org/apache/gobblin/cluster/HelixUtils.java	32.23% <0.00%> (-2.48%)	⬇️
...ore/util/DatabaseJobHistoryStoreSchemaManager.java	29.31% <0.00%> (-2.36%)	⬇️
... and 55 more

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[umustafi]

@arjun4084346 @jack-moseley can you review?

[arjun4084346]

+1 LGTM but not sure about the necessity of this metrics.

[umustafi]

@sv2000 can you merge?

[umustafi]

@aplex can you merge?