[jdk21u] RFR: 8312489: Increase jdk.jar.maxSignatureFileSize default which is too low for JARs such as WhiteSource/Mend unified agent jar

[Nibedita Jena]

Clean backport of https://bugs.openjdk.org/browse/JDK-8312489 (e47a84f23dd2608c6f5748093eefe301fb5bf750)

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Commit messages:
 - Backport e47a84f23dd2608c6f5748093eefe301fb5bf750

Changes: https://git.openjdk.org/jdk21u/pull/76/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk21u&pr=76&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8312489
  Stats: 9 lines in 2 files changed: 2 ins; 0 del; 7 mod
  Patch: https://git.openjdk.org/jdk21u/pull/76.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u.git pull/76/head:pull/76

PR: https://git.openjdk.org/jdk21u/pull/76