RFR: 8284775: Simplify String.substring(_, length()) calls

[Brian Burkhalter]

On Tue, 12 Apr 2022 19:38:33 GMT, Andrey Turbanov <aturbanov at openjdk.org> wrote:

> Default `to` index for String.substring method call is length of the String.
> We can simplify code a bit, by omitting default value.

Marked as reviewed by bpb (Reviewer).

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PR: https://git.openjdk.java.net/jdk/pull/8212