[jdk11u-dev] RFR: 8294941: GHA: Cut down cross-compilation sysroots

[Aleksey Shipilev]

Clean backport to improve 11u GHA overheads. It would be followed by another backport that would cut stuff even deeper: [JDK-8314262](https://bugs.openjdk.org/browse/JDK-8314262).

Additional testing:
 - [ ] GHA

-------------

Commit messages:
 - Backport a1747ef81a10e84177f474565193204ceaa0ede8

Changes: https://git.openjdk.org/jdk11u-dev/pull/2105/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2105&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8294941
  Stats: 3 lines in 1 file changed: 2 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2105.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2105/head:pull/2105

PR: https://git.openjdk.org/jdk11u-dev/pull/2105