Fixed UniqueConstraintSnapshotGenerator

[nvoxland]

Reverted a previous commit that assumed all databases support bulk-querying constraint columns. Then, incorporated changes from #1479 to increase the number of databases that do support them.

Fixes #1477

[wwillard7800]

Looks good

[codecov]

Codecov Report

Merging #1548 (4efdc0e) into 4.2.x (05257e8) will increase coverage by 0.00%.
The diff coverage is 0.00%.

@@            Coverage Diff            @@
##              4.2.x    #1548   +/-   ##
=========================================
  Coverage     49.59%   49.59%           
- Complexity     7862     7863    +1     
=========================================
  Files           757      757           
  Lines         37024    37025    +1     
  Branches       6699     6696    -3     
=========================================
+ Hits          18362    18364    +2     
  Misses        16232    16232           
+ Partials       2430     2429    -1     

Impacted Files	Coverage Δ	Complexity Δ
...napshot/jvm/UniqueConstraintSnapshotGenerator.java	5.55% <0.00%> (-0.03%)	4.00 <0.00> (ø)
...-core/src/main/java/liquibase/util/ObjectUtil.java	37.98% <0.00%> (+1.11%)	36.00% <0.00%> (+1.00%)

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