Improved retry logic for intermittent TLS1.2 issue

[ulvii]

Intermittent TLS1.2 issue details can be found here.

• Based on the discussion on The driver could not establish a secure connection to SQL Server by using Secure Sockets Layer (SSL) encryption. Error: "Unexpected rethrowing". #879 , changed the retry logic to also check for Exception cause because actual error message can be wrapped into a different message when re-thrown from underlying InputStream.
• Some minor cleanup.

[codecov-io]

Codecov Report

Merging #882 into dev will decrease coverage by 0.09%.
The diff coverage is 28.57%.

@@             Coverage Diff             @@
##                dev     #882     +/-   ##
===========================================
- Coverage     48.74%   48.65%   -0.1%     
+ Complexity     2813     2808      -5     
===========================================
  Files           118      118             
  Lines         27863    27869      +6     
  Branches       4637     4640      +3     
===========================================
- Hits          13582    13559     -23     
- Misses        12086    12115     +29     
  Partials       2195     2195

Flag	Coverage Δ	Complexity Δ
#JDBC42	48.2% <28.57%> (+0.01%)	2766 <0> (+2)	⬆️
#JDBC43	48.57% <28.57%> (-0.07%)	2804 <0> (-5)

Impacted Files	Coverage Δ	Complexity Δ
...in/java/com/microsoft/sqlserver/jdbc/IOBuffer.java	55.86% <28.57%> (-0.08%)	0 <0> (ø)
...om/microsoft/sqlserver/jdbc/ReaderInputStream.java	45.05% <0%> (-2.2%)	15% <0%> (ø)
...m/microsoft/sqlserver/jdbc/SQLServerResultSet.java	32.27% <0%> (-0.77%)	252% <0%> (-7%)
...rc/main/java/com/microsoft/sqlserver/jdbc/DDC.java	45.73% <0%> (-0.66%)	108% <0%> (ø)
...rc/main/java/com/microsoft/sqlserver/jdbc/dtv.java	62.45% <0%> (-0.12%)	0% <0%> (ø)
...n/java/com/microsoft/sqlserver/jdbc/DataTypes.java	79.48% <0%> (+0.19%)	5% <0%> (+1%)	⬆️
...n/java/com/microsoft/sqlserver/jdbc/Parameter.java	64.32% <0%> (+0.2%)	64% <0%> (ø)	⬇️
...ncurrentlinkedhashmap/ConcurrentLinkedHashMap.java	39% <0%> (+0.21%)	43% <0%> (ø)	⬇️

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