Suppress exception in Pub/Sub adapter in AUTO_ACK and MANUAL modes

[elefeint]

The current behavior of the Pub/Sub Spring Integration inbound adapter throwing an exception in AUTO_ACK and MANUAL modes results in client library reacting to the exception by nacking in its code.

This PR removes the exception and logs a warning instead, allowing the message to be redelivered according to Subscription ackDeadline setting and the client library's automatic deadline extension setting.

Fixes #2250.
Follow-up to #2074.

[codecov]

Codecov Report

Merging #2319 into master will increase coverage by 0.00%.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master    #2319   +/-   ##
=========================================
  Coverage     73.54%   73.54%           
  Complexity     2078     2078           
=========================================
  Files           258      258           
  Lines          7468     7469    +1     
  Branches        772      772           
=========================================
+ Hits           5492     5493    +1     
  Misses         1620     1620           
  Partials        356      356           

Flag	Coverage Δ	Complexity Δ
#unittests	73.54% <100.00%> (+<0.01%)	2078.00 <0.00> (ø)

Impacted Files	Coverage Δ	Complexity Δ
...tegration/inbound/PubSubInboundChannelAdapter.java	65.38% <100.00%> (+0.67%)	9.00 <0.00> (ø)

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[dzou]

Maybe add docs to clarify the behavior?

Thanks for getting to the bottom of this complicated issue; I know that users have always periodically posted questions asking about this so it is very helpful to clarify expected behavior.

[elefeint]

Yes, I am going to whip #2078 into shape next.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!

0 Bugs
0 Vulnerabilities (and 0 Security Hotspots to review)
0 Code Smells

100.0% Coverage
0.0% Duplication

[meltsufin]

Nice! I like the at least and at most check! :)