RFR: 8332086: Remove the usage of ServiceLoader in j.u.r.RandomGeneratorFactory

[Raffaello Giulietti]

All random number generator algorithms are implemented in module `java.base`. The usage of `ServiceLoader` in `j.u.r.RandomGeneratorFactory` is no longer needed.

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Commit messages:
 - 8332086: Remove the usage of ServiceLoader in j.u.r.RandomGeneratorFactory

Changes: https://git.openjdk.org/jdk/pull/19212/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19212&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8332086
  Stats: 204 lines in 4 files changed: 51 ins; 45 del; 108 mod
  Patch: https://git.openjdk.org/jdk/pull/19212.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19212/head:pull/19212

PR: https://git.openjdk.org/jdk/pull/19212