[jdk11u-dev] RFR: 8212726: Replace some use of drop- and foldArguments with filtering argument combinator in StringConcatFactory

[Anton Bobrov]

This is a backport of 06a2bb52747eab8033f53b45fad714eb649475f0 / [JDK-8212726](https://bugs.openjdk.org/browse/JDK-8212726)

This backport is needed to facilitate the backport of [JDK-8222852](https://bugs.openjdk.org/browse/JDK-8222852) which is otherwise very complex and high risk to rework for 11u-dev.

Aside from positional merge conflict in StringConcatFactory this is a clean backport
Testing: x86_64 build, tier1

Due to possible high exposure I'm running tier2 and tier3 as well to unsure safety for 11u-dev.

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Commit messages:
 - Backport 06a2bb52747eab8033f53b45fad714eb649475f0

Changes: https://git.openjdk.org/jdk11u-dev/pull/2800/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2800&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8212726
  Stats: 162 lines in 3 files changed: 91 ins; 32 del; 39 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2800.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2800/head:pull/2800

PR: https://git.openjdk.org/jdk11u-dev/pull/2800