Reject trailing characters in DecimalLocaleConverter.parse (1.X)

[rootvector2]

Port of #399 to the 1.X branch.

DecimalLocaleConverter.parse calls DecimalFormat.parse(String), which stops at the first character it cannot read and silently drops the rest, so a locale numeric conversion of 123abc returns 123 and 42 OR 1=1 returns 42. Every numeric locale converter (Byte/Short/Integer/Long/Float/Double/BigDecimal/BigInteger) routes through this one method, while the sibling DateLocaleConverter already rejects leftover input with a ParsePosition check. Switched to that same form so the whole string must be consumed, otherwise ParseException is thrown.

Added DecimalLocaleConverterTest (fails without the runtime change) and updated the now-stale (B) assertions across the numeric locale converter tests, which pinned DecimalFormat's old partial-parse values and now fall through to the converter default.

mvn test -Dtest='*LocaleConverterTest' is green (104 tests). The only failure in a full mvn run is LocaleBeanificationTest.testContextClassloaderIndependence, which is a pre-existing flake unrelated to this change (it fails the same way on a clean 1.X checkout and installs its own mock converters that bypass real parsing).

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[garydgregory]

Thank you @rootvector2 , merged 🚀