Fix #1818 add a system property for minimum login timeout

[bananayong]

Add system property for minimum login timeout, regardless of the connectionTimeout.

It will provide a consistent method for setting login timeout and minimum timeout that can be bigger(above 1s) than connectionTimeout.

Thank you!

[codecov]

Codecov Report

Merging #1820 (38ce5d3) into dev (8f254ae) will increase coverage by 0.01%.
The diff coverage is 100.00%.

@@             Coverage Diff              @@
##                dev    #1820      +/-   ##
============================================
+ Coverage     70.61%   70.62%   +0.01%     
  Complexity      572      572              
============================================
  Files            26       26              
  Lines          2178     2179       +1     
  Branches        311      311              
============================================
+ Hits           1538     1539       +1     
  Misses          486      486              
  Partials        154      154              

Impacted Files	Coverage Δ
src/main/java/com/zaxxer/hikari/pool/PoolBase.java	72.26% <100.00%> (+0.10%)	⬆️

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