[BPO] libreoffice 25.2.6 for jammy/noble

[Rico Tzschichholz]

[Impact]

 * LibreOffice 25.2.6 is in its sixth bugfix release of the 25.2 line:
     https://wiki.documentfoundation.org/ReleasePlan/25.2#25.2.6_release

 * This source packages matches the proposed SRU for plucky handled at
     https://bugs.launchpad.net/ubuntu/+source/libreoffice/+bug/2121789

[Scope]

 * Backport of https://launchpad.net/ubuntu/+source/libreoffice/4:25.2.6-0ubuntu0.25.04.1

 * Backport target is Jammy/22.04 LTS and Noble/24.04 LTS releases to provide an official build of a more recent upstream version of LibreOffice

[Testing]

 * Upstream testing. Bugs fixed upstream typically include unit/regression tests, and the release itself is extensively exercised (both in an automated manner and manually).

  * A recent set of upstream's automated jenkins testing can be found here:
    https://ci.libreoffice.org/job/gerrit_252/1100/

  * More information about the upstream QA testing can be found here:
    * Automated tests
      https://wiki.documentfoundation.org/QA/Testing/Automated_Tests
    * Automated UI tests
      https://wiki.documentfoundation.org/Development/UITests
    * Regression tests
      https://wiki.documentfoundation.org/QA/Testing/Regression_Tests
    * Feature tests
      https://wiki.documentfoundation.org/QA/Testing/Feature_Tests

 * Launchpad testing. The libreoffice packages include autopkgtests that were run and verified as passing.

   Jammy/22.04 https://launchpad.net/~libreoffice/+archive/ubuntu/ppa/+sourcepub/17539069/+listing-archive-extra
    * [amd64] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-ppa/jammy/amd64/libr/libreoffice/20250926_010823_679ff@/log.gz
    * [arm64] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-ppa/jammy/arm64/libr/libreoffice/20250925_183254_c49c3@/log.gz
    * [armhf] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-ppa/jammy/armhf/libr/libreoffice/20250925_170049_b0552@/log.gz
    * [ppc64el] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-ppa/jammy/ppc64el/libr/libreoffice/20250925_180644_9627c@/log.gz (no regression)
    * [riscv64] not available
    * [s390x] https://autopkgtest.ubuntu.com/results/autopkgtest-jammy-libreoffice-ppa/jammy/s390x/libr/libreoffice/20250925_220055_343ac@/log.gz (no regression)

   Noble/24.04 build at https://launchpad.net/~libreoffice/+archive/ubuntu/ppa/+sourcepub/17539068/+listing-archive-extra
    * [amd64] https://autopkgtest.ubuntu.com/results/autopkgtest-noble-libreoffice-ppa/noble/amd64/libr/libreoffice/20250925_172639_b8845@/log.gz
    * [arm64] https://autopkgtest.ubuntu.com/results/autopkgtest-noble-libreoffice-ppa/noble/arm64/libr/libreoffice/20250925_191142_57a20@/log.gz
    * [armhf] https://autopkgtest.ubuntu.com/results/autopkgtest-noble-libreoffice-ppa/noble/armhf/libr/libreoffice/20250925_173121_40a3d@/log.gz
    * [ppc64el] https://autopkgtest.ubuntu.com/results/autopkgtest-noble-libreoffice-ppa/noble/ppc64el/libr/libreoffice/20250925_170528_87bd5@/log.gz (no regression)
    * [riscv64] not available
    * [s390x] https://autopkgtest.ubuntu.com/results/autopkgtest-noble-libreoffice-ppa/noble/s390x/libr/libreoffice/20250925_170533_33ebc@/log.gz (no regression)

 * General smoke testing of all the applications in the office suite were carried out by going through the manual testplan as documented by: https://wiki.ubuntu.com/Process/Merges/TestPlans/libreoffice

[Regression Potential]

 * A combination of autopkgtests and careful smoke testing as described above should provide reasonable confidence that no regressions sneaked in.