Cleanup some Inefficiencies in JavaDateFormatter (#84922)

[pgomulka]

Fixes a couple of smaller inefficiencies that I found in profiling and otherwise.

• Iteration over the parsers is faster if we just use an array.
• Make some of the object construction more efficient since formats aren't always constants, like
  in e.g. the index name resolver.
• Fix non-static initializer block running useless puts into the static mutable map on every instantiation
  • no need to even have the map, just inline what it does and save some code, indirection and the
    iteration over the mutable map

backports #84922

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