Use already found dot index

[snuyanzin]

Also a bit speed up which gives about 10%
before

Benchmark                                      Mode  Cnt     Score     Error   Units
DatafakerExpressions.numberbetweenExpression  thrpt   10  3333.331 ± 246.507  ops/ms

after

Benchmark                                      Mode  Cnt     Score    Error   Units
DatafakerExpressions.numberbetweenExpression  thrpt   10  3666.636 ± 26.251  ops/ms

[codecov-commenter]

Codecov Report

Merging #546 (749a585) into main (a5eaa17) will increase coverage by 0.01%.
The diff coverage is 70.00%.

@@             Coverage Diff              @@
##               main     #546      +/-   ##
============================================
+ Coverage     92.65%   92.67%   +0.01%     
+ Complexity     2370     2369       -1     
============================================
  Files           247      247              
  Lines          4945     4944       -1     
  Branches        531      530       -1     
============================================
  Hits           4582     4582              
+ Misses          238      237       -1     
  Partials        125      125              

Impacted Files	Coverage Δ
.../java/net/datafaker/service/FakeValuesService.java	87.31% <70.00%> (-0.03%)	⬇️
...c/main/java/net/datafaker/providers/base/Text.java	78.81% <0.00%> (+0.84%)	⬆️

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