[GOBBLIN-1777] Register gauge metrics for change monitors

[umustafi]

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-1777

Description

• Here are some details about my PR, including screenshots (if applicable):
  Unlike other metrics gauges need to be registered. Quick fix to this.

Tests

• My PR adds the following unit tests OR does not need testing for this extremely good reason:

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 #3634 (75be6dd) into master (667d797) will decrease coverage by 10.51%.
The diff coverage is n/a.

@@              Coverage Diff              @@
##             master    #3634       +/-   ##
=============================================
- Coverage     46.56%   36.06%   -10.51%     
+ Complexity    10666     1480     -9186     
=============================================
  Files          2133      382     -1751     
  Lines         83541    15646    -67895     
  Branches       9288     1547     -7741     
=============================================
- Hits          38905     5642    -33263     
+ Misses        41074     9546    -31528     
+ Partials       3562      458     -3104     

Impacted Files	Coverage Δ
...ervice/monitoring/DagActionStoreChangeMonitor.java
...lin/service/monitoring/SpecStoreChangeMonitor.java
...lin/metastore/MysqlJobStatusStateStoreFactory.java
.../mapreduce/orc/OrcValueCombineFileInputFormat.java
...che/gobblin/writer/HiveWritableHdfsDataWriter.java
...n/java/org/apache/gobblin/salesforce/SfConfig.java
...blin/runtime/std/FilteredJobLifecycleListener.java
...bblin/password/EncryptedPasswordAuthenticator.java
...ker/task/TaskLevelPolicyCheckerBuilderFactory.java
...e/modules/orchestration/MysqlUserQuotaManager.java
... and 1742 more

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