[#2920] dead lock workaround

[emeroad]

#2920

• AppClassLoader and PinpointUrlClassLoader Circular dependency deadlock #2881 backport
• pre-load CollectJob

[codecov-io]

Codecov Report

Merging #2922 into 1.6.x will increase coverage by 0.09%.
The diff coverage is 71.42%.

@@            Coverage Diff             @@
##            1.6.x    #2922      +/-   ##
==========================================
+ Coverage   36.77%   36.87%   +0.09%     
==========================================
  Files        1780     1782       +2     
  Lines       61414    61435      +21     
  Branches     8594     8595       +1     
==========================================
+ Hits        22586    22654      +68     
+ Misses      36448    36401      -47     
  Partials     2380     2380

Impacted Files	Coverage Δ
...oint/profiler/monitor/DefaultAgentStatMonitor.java	73.07% <100%> (-10.26%)	⬇️
...corp/pinpoint/profiler/sender/EmptyDataSender.java	15.38% <15.38%> (ø)
...avercorp/pinpoint/profiler/monitor/CollectJob.java	90% <90%> (ø)
...npoint/rpc/server/SimpleServerMessageListener.java	80% <0%> (-20%)	⬇️
.../profiler/sender/StandbySpanStreamDataStorage.java	72.88% <0%> (-3.39%)	⬇️
...orp/pinpoint/rpc/server/DefaultPinpointServer.java	76.13% <0%> (+0.75%)	⬆️
...tor/metric/datasource/DefaultDataSourceMetric.java	75.75% <0%> (+6.06%)	⬆️
...m/navercorp/pinpoint/rpc/packet/RequestPacket.java	89.74% <0%> (+7.69%)	⬆️
... and 10 more

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