archive/tar: unbounded allocation when parsing GNU sparse map (CVE-2025-58183) [1.25 backport]

[gopherbot]

@neild requested issue #75677 to be considered for backport to the next 1.25 minor release.

@gopherbot please open backport issues for this security fix

[gopherbot]

Change https://go.dev/cl/709852 mentions this issue: [release-branch.go1.25] archive/tar: set a limit on the size of GNU sparse file 1.0 regions

[gopherbot]

Closed by merging CL 709852 (commit 2612dcf) to release-branch.go1.25.