Add work queue bound on LicenseException retries in RPMConnectionServ…

[kanderson250]

Fixes #1428

This PR addresses OutOfMemory exceptions that were reported during rotation to an invalid license key. The cause of the memory leak was found to be excessive creation of RPMConnectionTasks. To mitigate the issue, the number of RPMConnectionTasks created during processing of a LicenseException is now bounded.

• The ScheduledExecutorService is replaced with a ScheduledThreadPoolExecutor, in order to get access to the size of its work queue.
• The LicenseException handler in the doConnect method of RPMService limits reconnect attempts when the work queue acquires a certain number of tasks.
• The number of tasks is bounded at 5000.

There is no way for the agent to recover from a bad license key, so although these mitigation steps will prevent a memory leak, a JVM restart is still required to get the agent back up.

[codecov-commenter]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (c94127d) 70.61% compared to head (152ca75) 70.63%.
Report is 114 commits behind head on main.

Files	Patch %	Lines
...m/newrelic/agent/rpm/RPMConnectionServiceImpl.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1606      +/-   ##
============================================
+ Coverage     70.61%   70.63%   +0.02%     
- Complexity     9761     9913     +152     
============================================
  Files           814      826      +12     
  Lines         39313    39804     +491     
  Branches       5970     6011      +41     
============================================
+ Hits          27759    28115     +356     
- Misses         8866     8975     +109     
- Partials       2688     2714      +26     

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