[NFC][mlir][AsmPrinter] Don't compute resourceStr when --mlir-elide-resource-strings-if-larger=0 (#138275)
When skipping the printing of large DenseResourceElementsAttr with
--mlir-elide-resource-strings-if-larger,
we need to compute resourceStr to check if the string is small enough to
print.
With --mlir-elide-resource-strings-if-larger set to 0, nothing should be
printed, but we still compute the size.
This change will allow an early return when
--mlir-elide-resource-strings-if-larger=0, making the print process
faster.