[C++] Bump version of bundled boost to 1.81.0

[nealrichardson]

Describe the enhancement requested

In addition to bumping the version in versions.txt, we need to update our trimmed version that we host (90% smaller than the full boost). See cpp/build-support/trim-boost.sh. Edit BOOST_VERSION and/or provide on the command line. Then upload the bundle to artifactory (see https://issues.apache.org/jira/browse/ARROW-14336).

While you're in there, you should edit the comment about uploading to https://github.com/ursa-labs/thirdparty/releases/edit/latest, which we've switched off of. (It also appears in versions.txt but isn't used anywhere else anymore.)

May also need to edit Boost_ADDITIONAL_VERSIONS in ThirdpartyToolchain.cmake. Check for other places in that file too.

Component(s)

C++

[kou]

Could you use https://apache.jfrog.io/artifactory/arrow/thirdparty/ instead of https://github.com/ursa-labs/thirdparty/releases/edit/latest ?
We're using https://apache.jfrog.io/artifactory/arrow/thirdparty/ for mirror URL: https://github.com/apache/arrow/blob/master/cpp/cmake_modules/ThirdpartyToolchain.cmake#L424

All Apache Arrow committers/PMC members can upload a file to https://apache.jfrog.io/artifactory/arrow/thirdparty/ from https://apache.jfrog.io/ui/repos/tree/General/arrow/thirdparty with their ASF account.

[nealrichardson]

Agree @kou, part of this task should be to remove any vestigial references to the old ursalabs repo